IL9 and acute lymphoblastic leukemia: SHP2-deficiency also enhanced IL-7-induced phosphorylation of γcY357 (Fig. 5f) as well as IL-2-, IL-7- and IL-9-induced phosphorylation of STAT5Y694/Y699 in HPB-ALL and CTLL2 cells, respectively (Fig. 5f, g), suggesting that SHP2 negatively regulates γc family cytokine-triggered signaling.