PBX1 and acute lymphoblastic leukemia: Recently, it was shown that ALL subtypes are associated with differential accumulation of MTX-PG levels: ALL harboring TCF3-PBX1 or ETV6-RUNX1 fusions presented lower MTX-PG levels, whereas hyperdiploid and BCR-ABL-like ALL had higher MTX-PG levels than other subtypes (10).