TP53 and cancer: In line with this, the CDK5 siRNA increased cancer cell G1 cell cycle arrest and apoptosis, however knockdown of TP53 reduced the CDK5 siRNA-induced G1 cell cycle arrest in the presence or absence of paclitaxel (Fig 3E and 3G) and decreased the CDK5 siRNA-induced apoptosis (Fig 3F and 3G) in HEY cells.