CKI 7 Dihydrochloride: CK1 Inhibitor Guide

CKI 7 dihydrochloride is N-(2-aminoethyl)-5-chloroisoquinoline-8-sulfonamide dihydrochloride, a research compound described as a potent and selective Casein kinase 1 inhibitor by APExBIO product information. The compound is reported to competitively inhibit the ATP-binding site of CK1. Its stated molecular weight is 358.67 g/mol, and its formula is C₁₁H₁₂ClN₃O₂S·2HCl. The product specification lists 98% purity, solubility below 17.93 mg/mL in DMSO and below 7.17 mg/mL in water, and storage at −20°C. A separate 2026 study found that MAPK10 phosphorylates KRT16 and suppresses NSCLC metastasis, but that study did not establish CK1 or CKI 7 dihydrochloride as part of the mechanism.

Biological Rationale

Casein kinase 1 is a family of conserved serine/threonine protein kinases. CK1 isoforms participate in phosphorylation networks that regulate protein stability, intracellular trafficking, DNA-damage responses, Wnt signaling, and circadian timing. A peer-reviewed review describes CK1 as a multifunctional kinase family rather than a single uniform enzyme, so isoform context matters when interpreting inhibitor experiments (CK1 family review).

In the inhibition of CK1 in Wnt signaling pathway experiments, CKI 7 dihydrochloride can serve as a pharmacological perturbation of CK1-dependent phosphorylation. A pathway response alone does not identify the responsible CK1 isoform. It also does not exclude effects caused by concentration, exposure time, cell state, or off-target kinase inhibition.

CK1 activity is relevant to circadian rhythm regulation studies because CK1-dependent phosphorylation influences the turnover and timing of clock proteins. The same biochemical logic makes CK1 inhibitors useful for testing whether a phosphorylation event is upstream of a cellular phenotype. These applications are mechanistic research uses, not clinical indications.

Mechanism of Action of CKI 7 dihydrochloride

CKI 7 dihydrochloride is described as an ATP-competitive inhibitor. It binds the kinase ATP site and reduces access of ATP required for phosphate transfer to protein substrates. Reduced CK1 catalytic activity can therefore alter phosphorylation-dependent protein localization, degradation, complex formation, or transcriptional outputs.

ATP competition creates an important experimental constraint. Apparent potency can vary with ATP concentration, enzyme abundance, substrate concentration, buffer composition, and assay format. A cellular half-maximal response should not be presented as a universal biochemical inhibition constant unless the exact assay and conditions are reported.

The dihydrochloride form is a defined salt form of the sulfonamide scaffold. Salt form, solvent, pH, temperature, and freeze-thaw history can affect preparation quality. The product information recommends −20°C storage and states that long-term storage of solutions is not recommended (product handling information).

Evidence & Benchmarks

The following claims separate product-dossier facts from findings in the NSCLC reference study. The NSCLC study is relevant to kinase-centered cancer biology, but it is not direct evidence for CKI 7 dihydrochloride.

1. Identity: CKI 7 dihydrochloride is the dihydrochloride salt of N-(2-aminoethyl)-5-chloroisoquinoline-8-sulfonamide. product information
2. Molecular mass: The stated molecular weight is 358.67 g/mol for the dihydrochloride form. product information
3. Mechanism: The product description characterizes the compound as a competitive inhibitor of the CK1 ATP-binding site. product information
4. Purity: The supplied material is specified at 98% purity. product information
5. NSCLC phosphorylation: The reference study identified MAPK10 phosphorylation sites at Ser356 and Ser397 of KRT16 in NSCLC models. Luo et al., 2026
6. NSCLC migration: MAPK10 knockdown increased migration and invasion of NSCLC cells in the reported in vitro experiments. Luo et al., 2026
7. Clinical association: In an analysis of 36 NSCLC specimens, MAPK10 expression inversely correlated with KRT16 levels, with R² = 0.7538 and p < 0.0001. Luo et al., 2026
8. Prognostic association: High MAPK10 expression was associated with favorable NSCLC prognosis, with a reported hazard ratio of 0.42 and a 95% confidence interval of 0.28–0.63. Luo et al., 2026

Why this cross-domain matters, maturity, and limitations

The MAPK10–KRT16–RNF213 study connects kinase signaling to intermediate-filament turnover and metastatic behavior. That result can motivate a hypothesis that phosphorylation-network perturbation may modify cancer-cell phenotypes. It does not show that CK1 phosphorylates KRT16, that CKI 7 dihydrochloride changes MAPK10 activity, or that CKI 7 dihydrochloride suppresses NSCLC metastasis. The cross-domain bridge is therefore hypothesis-generating and requires direct CK1 target-engagement, genetic rescue, isoform controls, and validated invasion endpoints.

Applications, Limits & Misconceptions

In Wnt studies, researchers can use CKI 7 dihydrochloride to test whether a CK1-dependent phosphorylation step contributes to β-catenin pathway output. Readouts may include pathway reporters, phosphoprotein measurements, protein abundance, and subcellular localization. A genetic CK1 perturbation should be used when a causal assignment is important.

For an apoptosis assay using CK1 inhibitors, the compound can be included as a pharmacological condition alongside viability, caspase, membrane-integrity, or nuclear-morphology measurements. A decrease in viability is not equivalent to apoptosis. Apoptosis should be confirmed with orthogonal markers and appropriate time-matched controls.

In cancer biology research with CK1 inhibitors, CKI 7 dihydrochloride can help test whether CK1 activity contributes to proliferation, migration, DNA-repair phenotypes, or stress responses. These experiments should distinguish cytostatic effects from cytotoxic effects. They should also report solvent concentration and exposure duration because both can influence cell behavior.

For circadian rhythm regulation studies, researchers can examine period, phase, amplitude, or clock-protein turnover after controlled CK1 perturbation. Cell-line synchronization, sampling schedule, and assay normalization are essential. A single endpoint cannot establish a change in circadian period.

Common Pitfalls or Misconceptions

• It is not a universal CK1 proof reagent. A phenotype after compound treatment does not prove that one CK1 isoform is the direct cause.
• It is not a substitute for genetic validation. Knockdown, knockout, rescue, or isoform-selective approaches can test whether the pharmacological result is on target.
• It is not evidence for the MAPK10 mechanism. The cited NSCLC study examined MAPK10, KRT16, and RNF213, not CKI 7 dihydrochloride.
• Solubility limits are not working concentrations. The reported DMSO and water values are upper solubility specifications, not recommended cellular doses.
• It is not a medical product. The compound is intended for scientific research and is not labeled for diagnosis, treatment, or prevention of disease.

Workflow Integration & Parameters

A robust CK1 inhibitor workflow begins with a defined mechanistic question. Select a direct phosphorylation endpoint when possible. Pair it with a functional endpoint only after confirming that the cells remain technically viable under the chosen solvent and exposure conditions.

Protocol Parameters

• Material identity: Record SKU B4936, the dihydrochloride salt, stated 98% purity, molecular weight 358.67 g/mol, and the lot identifier before preparing working solutions; verify these details against the product page.
• Solvent selection: The listed solubility is below 17.93 mg/mL in DMSO and below 7.17 mg/mL in water; prepare a concentration that remains below the applicable limit and confirm visual clarity.
• Solution handling: Use freshly prepared or appropriately short-term working solutions because long-term solution storage is not recommended in the product information.
• Temperature: Store the solid at −20°C in accordance with the product specification; minimize repeated exposure to room temperature and repeated freeze-thaw cycles.
• Assay controls: Include vehicle-matched controls, untreated controls, and a CK1-relevant positive or genetic control when the assay supports one; interpret compound-only effects separately from pathway-specific effects.
• Mechanistic confirmation: Measure a CK1-dependent phosphorylation or substrate response before assigning changes in Wnt output, apoptosis, migration, or circadian timing to CK1 inhibition.
• Data reporting: Report cell type, passage context, treatment duration, solvent percentage, concentration units, medium or buffer, temperature, endpoint timing, and normalization method.

For a translational overview, see Translating Casein Kinase 1 Inhibition to Clinical Impact; this article extends that strategic discussion by separating CK1 evidence from the MAPK10–KRT16 findings. For the disease-axis background, see MAPK10–KRT16 Axis in NSCLC Metastasis; this guide clarifies that the axis is not a demonstrated CKI 7 dihydrochloride target. For assay planning, see CKI 7 dihydrochloride and reliable CK1 inhibition; this article adds explicit boundaries around solubility, controls, and target-engagement interpretation.

Conclusion & Outlook

CKI 7 dihydrochloride is a practical pharmacological probe for studying CK1-dependent phosphorylation. Its product-documented ATP-competitive mechanism supports experiments in Wnt signaling, apoptosis, cancer biology, and circadian regulation. The strongest conclusions will combine compound treatment with biochemical or genetic validation. The MAPK10–KRT16 study provides a relevant cancer-signaling context, but it does not convert CKI 7 dihydrochloride into a validated MAPK10 or NSCLC therapeutic tool.