A possible explanation for these contradictory reports could be that TCF1 may act as a tumor suppressor in certain subgroups of pediatric T-ALL [including Early T-cell precursor (ETP)-ALL and myocyte enhancer factor 2C (MEF2C) positive T-ALL] and as an oncogene in other groups of T-ALL. Here, MEF2C is linked to acute lymphoblastic leukemia.