MEF2D and acute lymphoblastic leukemia: Interestingly, FLT3 expression seems to be linked to B-cell differentiation stages of ALL, higher in immature ALLs (KMT2A-r and ZNF384-r) and lower in the more mature subtypes (ETV6-RUNX1, TCF3-PBX1, and MEF2D-r) (Supplementary Fig. 7).