HIF1A and hepatocellular carcinoma: The interaction of these HREs with the HIF-1 or HIF-2 protein mediates the transcription of the PAI-1 gene that is involved in invasion and metastasis.88 However, Yang et al. reported recently that high HIF-2α expression was found in only 13.5% (17/126) of tumors compared with 47.6% (60/126) of peritumoral tissues in HCC samples.