CDK4 and hepatocellular carcinoma: Advances in gene expression profiling have provided new insights into the molecular genetics of HCC, showing strong expression signatures of cell proliferation and antiapoptosis genes (such as PNCA and cell cycle regulators CDK4, CCNB1, CCNA2, and CKS2) along with genes involving ubiquitination [32], as well as unique molecular markers of progression like HSP70, CAP2, GPC3, and GS [33].