p53 gene Repair Division with damage before division (mutation,aneuploidy) DNA p53 level DNA No p53 Tumor damage rises damage No G G arrest arrest or apoptosis Mitotic failure and cell death (a) (b) (c) Atter D.P.Lane,reprinted with permission from Nature 358:15.1992 Copyright 1999 John Wiley and Sons,Inc.Ail rights reservedp53 gene