APAF1 and leukemia: For example, epigenetic regulation of Apaf-1 via its promoter methylation is associated with apoptosis resistance in malignant melanoma cells [8] as well as in some leukemias [9, 10]; however, in another study, inactivation of Apaf-1 was not corroborated in malignant melanoma [11] Defective apoptosome formation through LOH-mediated repression of Apaf-1 has also been reported in glioblastoma [10] and Apaf-1 hypermethylation has been seen in bladder cancer [12].