AFF1 and acute lymphoblastic leukemia: 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).