Binding and antagonism of chemokines. (A) Displacement of 125I-labeled CXCL1/GROα (125I-GRO) by agonists. COS-7 cells were transfected with 5 μg of cDNA encoding mORF74. Forty-eight hours after transfection, 125I-labeled CXCL10/GROα binding was determined in the presence of increasing concentrations of unlabeled CXCL1/GROα, KC, or MIP-2. (B) Displacement of 125I-labeled CXCL1/GROα (125I-GRO) by human and murine IP-10 (hIP-10 and mIP-10, respectively). COS-7 cells were transfected with 5 μg of cDNA encoding mORF74. Forty-eight hours after transfection, 125I-labeled CXCL10/GROα binding was determined in the presence of increasing concentrations of unlabeled hCXCL10/IP-10 or mCXCL10/mIP-10. (C) Antagonism of mIP-10 on mORF74. COS-7 cells were transfected with 2 μg of cDNA encoding mORF74 and 5 μg of pTLNC-21CRE. Eighteen hours after transfection, forskolin (10−5 M), MIP-2 (10−7 M), and mIP-10 (3 × 10−7 M) were added. Twenty-four hours after transfection, CRE-driven luciferase expression was determined. In all panels, a representative experiment performed in triplicate is shown. Each experiment was repeated at least two times.