FOS and leukemia: Consistent with this concept, we demonstrated that resistance to apoptotic cell death induced by VM-26 was accompanied by attenuated c-Jun/AP-1 activation and a lack of DNA damage-induced responses by constitutively mutant p53 in the apoptotic signaling pathway in atypical multidrug resistance (at-MDR) leukemia cells with altered topoisomerase IIα [115,165].