ENDOG and leukemia: Endonuclease G (ENDOG), a nuclear encoded enzyme that localizes to mitochondria, is involved in nuclear DNA cleavage during early apoptotic processes [26], limited breakage during stress [27], and cleavage of the leukemia-associated breakpoint cluster region in the Mixed Lineage Leukemia gene (MLL), which requires activity of the BER protein APE1 [28].