Casein kinase 1 isoform alpha, Casein kinase 1 isoform delta, and Casein kinase 1 isoform epsilon (CK1α, CK1δ, CK1ε)

Casein kinase 1 isoforms alpha, delta, and epsilon are members of the conserved casein kinase 1 family of serine/threonine protein kinases, each encoded by distinct genes (CSNK1A1, CSNK1D, CSNK1E). They phosphorylate diverse substrate proteins and act as key regulators in multiple cellular pathways—including the Wnt/β-catenin signaling pathway, cell cycle control, and circadian rhythm maintenance. Their functions extend to DNA repair, apoptosis, cell migration, and immune responses. CK1 isoforms are implicated in cancer, neurodegenerative diseases, and circadian rhythm disorders. The family has therapeutic relevance, with CK1α directly targeted by drugs such as lenalidomide in cancer, and inhibitors of CK1δ and CK1ε under preclinical development. Their ability to broadly modulate key cellular pathways presents both opportunities for therapy and challenges for safety.

Other names

CK1alphaCK1deltaCK1epsilonCasein kinase I alpha/delta/epsilonCSNK1A1 (CK1α gene)CSNK1D (CK1δ gene)CSNK1E (CK1ε gene)Casein kinase 1 subfamilyFormer abbreviation CK1 (for the class/family)

Inhibition of kinase activity (small-molecule kinase inhibitors); Induced degradation (e.g., lenalidomide causes ubiquitination of CK1α); Blockage of phosphorylation of key downstream substrates, leading to modulation of cell signaling or cell death pathways