HIF-1α forms a weak complex with Myc in vivo. (A, B) ΔODD and Myc, as indicated, were co-expressed in 293 cells. Co-immunoprecipitations with antibodies against HA (α-HA IP) or Myc (α-Myc IP) were performed, followed by Western analyses detecting co-immunoprecipitates (marked with arrow heads), as well as immunoprecipitates. Input, whole-cell extracts subjected to direct Western analysis. (C) Omission of antibody (−Ab) and use of normal immunoglobulin (IgG) were included as controls for an anti-Myc co-immunoprecipitation. (D) The interaction of endogenous HIF-1α and Myc in HCT116 cells was shown in an anti-HIF-1α co-immunoprecipitation, followed by anti-Myc Western blotting.