STAT5A and mature T-cell and NK-cell non-Hodgkin lymphoma: Furthermore, STAT molecules have been shown to be constitutively activated in some hematologic malignancies, including STAT5 in several subtypes of PTCL, ~35% of cases of HSTL, 2% of T-LGL, and ~6% of pediatric T-ALL often leading to worse patient outcomes [8, 12, 47, 48].