Functional inhibition of MIF-1 and MIF-2 by MIF098 and 4-CPPC.
A, MIF098 selectively inhibits MIF-1 tautomerase activity compared with MIF-2 measured by HPP tautomerization. B and C, MIF-2–CD74 (B) and MIF-1–CD74 (C) binding assay using biotinylated human MIF-2 or biotinylated human MIF-1 and immobilized recombinant sCD74. Anti-MIF-1 antibody, anti-MIF-2 antibody, human MIF-1 (hMIF-1), human MIF-2 (hMIF-2), 4-CPPC, and MIF098 were added at increasing concentrations, and biotinylated MIF-2 binding/MIF-1 binding to sCD74 was revealed by detection of streptavidin-conjugated alkaline phosphatase. Nonreactive IgG served as a negative control. D and E, selective inhibition by 4-CPPC or MIF098 of MIF-2 (D) and MIF-1 (E) stimulated phosphorylation of ERK1/2 in cultured human fibroblasts.