Given that BCL2 is a key anti-apoptotic gene and MYC is a master regulator of cell proliferation and stress response, their abnormal high expression may potentially contribute to chemotherapy resistance in MLL/AF4+ children—this inference is supported by previous studies showing that overexpression of BCL2 or MYC correlates with reduced sensitivity to chemotherapy in pediatric ALL (33). This evidence concerns the gene KMT2A and acute lymphoblastic leukemia.