Owing to the significant rate of STAT5B mutations in 9 different T cell cancers, which exhibit STAT5 activation status and the essential genetic role for STAT5 in T cell differentiation, function, proliferation, and survival, we postulate that our findings in T-ALL extend to the large group of approximately 30 different mature T cell cancers (such as PTCL) (59). This evidence concerns the gene STAT5B and acute lymphoblastic leukemia.