CDK5 and hepatocellular carcinoma: In hepatocellular carcinoma tumors, HIF-1α promotes angiogenesis through transcriptional activation of downstream target genes including VEGFA, VEGFR1, and EphA1. Inhibition of HIF-1α-binding protein CDK5 can suppress the transcriptional activity of HIF-1α, leading to downregulation of HIF-1α downstream angiogenic target genes and inhibition of angiogenesis in hepatocellular carcinoma [21].