GSK-3β phosphorylates HIF-1α and induces its ubiquitylation. (A) HIF-1α was immunoprecipitated from GSK-3β^+/+ and GSK-3β^−/− cells and phospho HIF-1α protein levels were measured with the Pro-Q Diamond Phosphoprotein Gel Stain. The phospho HIF-1α protein levels from GSK-3β^+/+ cells were set to 100%. Values are means ± SEM of 3 independent experiments. *Significant difference between GSK-3β^+/+ versus GSK-3β^−/−. (B) Representative Pro-Q Diamond Phosphoprotein Gel Stain analysis. (C) HIF-1α was immunoprecipitated (IP) from GSK-3β^+/+ and GSK-3β^−/− cells and ubiquitylation was analyzed by immunoblotting (IB) with ubiquitin Abs. WCE indicates whole-cell lysates.