Skip to main content
. 2007 Feb 6;104(7):2301–2306. doi: 10.1073/pnas.0608382104

Fig. 5.

Fig. 5.

In vitro analysis of the ability of HIF-1α and HIF-2α to induce EPO mRNA transcription. (A) siRNA knockdown of HIF-1α and HIF-2α. Western blot for HIF-1α and HIF-2α shows stabilization of the protein under hypoxia (H) and specific loss of the appropriate protein after siRNA transfection. (B) EPO mRNA levels in Hep3B cells. Fold change of mRNA under hypoxia compared with normoxic cells. Nontransfected cells and cells transfected with control siRNA show a 55-fold induction of EPO mRNA under hypoxia. Knocking-down HIF-1α results in a 45-fold increase in EPO mRNA. In contrast, siRNA against HIF-2α resulted in a 5-fold induction and knocking-down both HIFs almost completely ablates EPO mRNA induction under hypoxia. (C) A mutated (“TM”) and therefore stabilized form of HIF-1α and HIF-2α was introduced into Hep3B cells at increasing concentrations, resulting in a strong induction of EPO mRNA for HIF-1α and a less prominent induction for HIF-2α. (D) Western blot displaying the levels of overexpressed protein.