PTPN2 and T-cell acute lymphoblastic leukemia: Kleppe and colleagues demonstrated that PTPN2 regulates T-cell proliferation via JAK/STAT signaling in patients with T-cell acute lymphoblastic leukemia (T-ALL), and they hypothesized that PTPN2 expression correlates with tumor response to the tyrosine kinase inhibitor imatinib (11, 12, 36).