STAT5B and prolymphocytic leukemia: The N642H mutation on STAT5b has also been identified as a driver mutation in both adult and pediatric acute lymphoblastic leukemia (T-ALL) prolymphocytic leukemia, NK/T cell lymphoma, and enteropathy-associated T cell lymphoma [24,25,26,27], whereas STAT5b T628S, Y665F, and V712E mutations have been discovered in multiple cases [24,27].