CDK18 and colorectal cancer: Depletion of CDK18, in colorectal cancer cells, increased endogenous DNA damage and chromosomal abnormalities (stalled replication forks), in response to replication stress mainly due to the activation ATR signaling pathway.467 Mechanistically, CDK18 interacts with RAD9, and RAD17, retaining them in the chromatin, a process involved in the regulation of replication stress signaling.