Phosphorylation of p53 at ser-15 by ATM kinase In response to DNA damage due to ionizing radiation, the serine at position 15 of the p53 tumor suppressor protein is rapidly phosphorylated by the ATM kinase. This serves to stabilize the p53 protein. A rise in the levels of the p53 protein induce the expression of the p21 cyclin-dependent kinase inhibitor. This prevents the normal progression from G1 to S phase, thus providing a check on replication of damaged DNA. Pubmed9733514 Pubmed9733515 Pubmed9843217 Reactome Database ID Release 4369511 Reactome, http://www.reactome.org ReactomeREACT_1756 Reviewed: Sanchez, Y, 2008-05-07 22:09:03