Figure 2.

RT-PCR analysis of changes in the expression of the indicated senescence-associated genes. β-actin was used as a normalization standard. (A) Gene expression in proliferating (PKH2^lo) and senescent (PKH2^hi) populations of HCT116 cells, separated 9 days after doxorubicin treatment. (B) Gene expression in the unsorted populations of wild-type, p21−/−, and p53−/− HCT116 cells, before and after 24-hr treatment with 200 nM doxorubicin, and on the indicated days after release from the drug. Genes were designated as p53- or p21-dependent if changes in their expression became detectable at a later day or were less pronounced in the p53−/− or p21−/− lines than in the wild-type cells.