Rcho-1 cells were transfected with PGK-1-HRE luciferase reporter and pRL-CMV, pRL-SV40, or pRL-TK constitutive luciferase reporter and either pc3DNA, pEGFP-N1 (as an internal control), or pc3HIF-1α 3xSDM, or mock transfected, as indicated. Samples were maintained in normoxia (21% oxygen) for 24hrs and analyzed for, (A) constitutive reporter activation and (C) PGK-1-HRE reporter. Results are average of three independent experiments. Luciferase activity at each concentration was analyzed and is shown relative to activity at 21% oxygen. Error bars represent standard deviation. Significance was denoted as *p≤0.01 was determined using a one way Anova with Tukeys post hoc test. (B) Nuclear extracts were collected, separated by SDS-PAGE, and Western blotting was performed using a polyclonal HIF-1α antibody and the appropriate secondary antibody as indicated in the Materials and Methods. The same blot was reprobed with actin monoclonal antibody for equal protein loading. Arrows identify HIF-1α and actin. The figure is a representative of three independent experiments.