MDM4 has been reported to be amplified in a small subset of aggressive HBs, and over expressed in HCN-NOS and HCC.4,7RPS6KA3 gene (Xp22.12) encodes a serine/threonine-protein kinase, ribosomal S6 protein kinase 2 (RSK2), that acts downstream of MAPK1/ERK2 signaling to mediate feedback inhibition. Here, MDM4 is linked to hepatocellular carcinoma.