RPS6KB1 and hepatocellular carcinoma: The USP7/ZNF638 axis selectively increases the cleavage of SREBP1C through AKT/mTORC1/S6K signaling, forming a USP7/ZNF638/SREBP1C nuclear complex. This complex regulates lipogenic enzymes, contributing to the progression of lipogenesis-related hepatocellular carcinoma