Regulation of TCR signaling by THEMIS. (A) Phosphorylation of ZAP-70 induced by treatment with 20 mM hydrogen peroxide in CD4⁺ T cells, as determined by intracellular flow cytometry. (B) Average mean fluorescence intensity of phosphorylated ZAP-70 in CD4⁺ T cells, exhibiting transient phosphorylation after hydrogen peroxide treatment. Data are expressed as means of 3 independent individuals with SD. (C) Experimental protocol for establishment of HTLV-1–infected cell lines exogenously expressing THEMIS and induction of ZAP-70 phosphorylation. (D) Immunoblots showing changes in the phosphorylation pattern of ZAP-70. TL-Om1 cells exogenously expressing THEMIS were isolated and treated with hydrogen peroxide for the indicated times. (E) Immunoblots showing downregulation of phosphorylation of PLCγ1 in MT-2 cells by exogenously expressed THEMIS under normal growth conditions.