CHEK2 and neoplasm: In contrast, the mutated gene set for the second, larger tumor class encompasses numerous genes involved in DNA damage checkpoints and damage-induced apoptosis (hereafter, for brevity, apoptosis set, Supplementary Fig. 6), primarily, TP53 and the associated apoptosis and checkpoint factors, such as BCL3, BRCA2, CHEK2, PML, TOPORS, TP63, AEN, and SIRT1, which are involved in the P53-dependent damage response.