Blockade of CXCR3-expressing 300-19 cell calcium mobilization by prior treatment with IRBP or S-Ag. CXCR3-expressing cells were stimulated with CXCL11 at 0.1 μg/mL and showed calcium mobilization (navy blue line). However, neither S-Ag (brown line) nor IRBP (green line) alone induced calcium mobilization of CXCR3-expressing cells and blocked CXCL11-induced calcium flux. Pretreatment of cells with CXCL11 blocked subsequent CXCL11-induced calcium mobilization (purple line).