Ca²⁺ responses of mutant Jurkat cell lines to TR agonists. Indo-1–loaded cells were stimulated with the indicated concentrations of thrombin (○, •) or SFLLRN (□, ▪). (A) Jurkat (open symbols) and J.RT-T3.5 (TCR-negative; solid symbols); (B) J.CaM1/lck (open symbols) and J.CaM1/rep3 (lck-deficient; solid symbols); and (C) J45/CH11 (open symbols) and J45.01 (CD45-deficient; solid symbols). Values represent the mean ± SD of triplicate determinations.