YAP1 and hepatocellular carcinoma: Exosomal circPAK1 from HCC cells competes for binding sites between 14-3-3ζ protein and YAP, which may impair the recruitment and cytoplasmic fixation of 14-3-3ζ to YAP and promote the cytoplasmic localization of YAP, which is a switch protein that plays a central role in the Hippo signaling pathway.