CHEK1

CHEK1, also known as CHK1 or OZEMA21, is a member of the Ser/Thr protein kinase family encoded by a human gene and is crucial for checkpoint regulation that halts the cell cycle in response to DNA damage or the presence of unreplicated DNA. CHEK1 integrates signals from ATM and ATR, two cell cycle proteins involved in the DNA damage response, which are also chromatin-associated during prophase I of meiosis. The phosphorylation of the CDC25A protein phosphatase by CHEK1 is necessary for delaying cell cycle progression in response to double-strand DNA breaks. CHEK1 is involved in DNA damage checkpoint signaling, the G2/M transition of the mitotic cell cycle, and the proliferation of inner cell mass cells. It functions in chromatin, the nucleus, and at replication forks and is expressed in various tissues, including adrenal medulla, early pregnancy, gonads, intestine, and trunk mesenchyme derived from the neural crest. Abnormal expression of CHEK1 is associated with various cancers, including pancreatic cancer.