HIF1A and hepatocellular carcinoma: Since YAP is a transcriptional activator in the Hippo signaling, and can also be inhibited by Hippo signaling [8], we then retrieved data on 369 HCC cases from The Cancer Genome Atlas (TCGA) to analyze the relationship between YAP mRNA and HIF-1α mRNA expression, and found a positive correlation between the two (R = 0.5, P = 1.7E-24) (Fig. 2b).