The Chk (Checkpoint kinase) family includes Chk1 and Chk2, both of which play a central role in the cellular response to DNA damage. Chk1 and Chk2 are primarily located in the nucleus, where they detect DNA damage and activate repair mechanisms to maintain genomic stability. These kinases regulate cell cycle checkpoints, particularly during DNA replication and mitosis, to prevent cells with damaged DNA from progressing to the next cycle. The expression and activity of Chk proteins are tightly regulated, and mutations are frequently associated with the development of cancers, especially in terms of inhibiting tumor growth and promoting apoptosis.