Inactivation of Apaf-1, a key effector of the intrinsic apoptosis pathway, and its effect on chemotherapy have been observed in several tumour types, including gastrointestinal cancer, leukemia, ovarian cancer and melanoma (Yamamoto et al, 2000; Jia et al, 2001; Soengas et al, 2001; Wolf et al, 2001; Liu et al, 2002). Here, APAF1 is linked to leukemia.