CK1δ is a regulator of Yes-associated protein (YAP) transcription coactivator, which is a key regulator of organ size and a candidate human oncogene. CK1d is activated by CCK2R and it then phosphorylates polycystin 2 (PKD2) at Ser244. Phosphorylation of PKD2 leads to its nuclear accumulation and efficient phosphorylation of nuclear PKD2 substrates in human gastric cancer cells. CKId can phosphorylate in vitro deoxycytidine kinase (dCK), which is a key enzyme in the salvage of deoxynucleosides. Phosphorylation of dCK by CKId in vitro correlates with increased activity of this enzyme.
