The MIF-3 site is a functional hypoxia-responsive element. A, Relative luciferase activity in CEMC7A cells transfected with the indicated constructs. Cells were grown under hypoxic conditions for 20 hours or in control cultures (under normoxic conditions). After incubation, luciferase assays were performed, and luciferase values were normalized to protein content. Bars show the mean and SD. * = P < 0.01 versus cells grown under normoxic conditions. NS = not significant. B, Percentage induction of MIF promoter activity in the groups shown in A, where 100% represents hypoxic induction of wild-type 71 MIF, to aid comparison of the hypoxic induction of each of the constructs. Bars show the mean and SD. * = P < 0.01 versus 71 MIF. C, Fold induction of MIF promoter activity over control in CEMC7A cells transfected with the 71 MIF construct and treated with phorbol myristate acetate (PMA) or tumor necrosis factor (TNF) or grown under hypoxic conditions. Cells were treated for 20 hours prior to harvesting, when luciferase assays were performed. Luciferase values were normalized to protein content. Bars show the mean and SD. * = P < 0.01 versus control. See Figure 1 for other definitions.