Regulation of IL-17 and IL-21 secretion in human T cells is ROCK2-dependent. Peripheral blood CD4+ T cells were treated with selective ROCK2 inhibitor KD025 (A and C) or with pan ROCK inhibitor Y-27632 (D) for 1 h and then stimulated by anti-CD3/28 mAbs alone (A and B) or in combination with IL-1β and TGF-β (C and D). IL-21, IL-17, and IFN-γ secretion was analyzed by ELISA after 48 h (A–D). CD4+ T cells were transfected with siRNA targeting ROCK1 and ROCK2 or with control siRNA and plated on anti-CD3/28 mAbs. After 48 h, ROCK1 and ROCK2 expression was defined by Western blot analysis (B, Left), and cytokine secretion was measured by ELISA (B, Right). The average of four different experiments is shown (A–D). *P < 0.05 and **P < 0.01 were calculated by t test.