Figure 4a: Hypoxia-inducible gene regulation by HIF-αIn normoxia, HIF-αis transcriptionally inactive and is rapidly degraded by the ubiquitin (Ub) proteasome pathway. In hypoxia, HIF-αundergoes protein stabilization and translocation from the cytoplasm to the nucleus, where it dimerizes with HIF-β to induce the transcription of related genes.