(B) The apoptotic response in U2OS cells with expression of wild-type and mutant KLF4. U2Os cells with wildtype (pLenti-tet-on-KLF4WT) or mutant (pLenti-tet-on-KLF4YYR/AAA) KLF4 were incubated with 10 ng/ml doxycycline for 24h and then treated with 10uM doxorubicin (Dox) or cisplatin (CDDP) for additional 24h. While expression of wild-type KLF4 decreases Bax expression and inhibits drug-induced PARP1 cleavage, expression of PARylation-deficient KLF4 leads to failure in inhibiting genotoxic-induced Bax expression and PARP1 cleavage. 