Upregulator Of Cell Proliferation (URGCP)

URG4 is upregulated in the presence of hepatitis B virus (HBV)-encoded X antigen (HBxAg) and may contribute to the development of hepatocellular carcinoma by promoting hepatocellular growth and survival .In patients infected with HBV, URG4 expression was higher in nontumor tissue than in tumor cells. URG4 localized to the cytoplasm and, in infected patients, colocalized with HBxAg. In unaffected individuals, URG4 protein distribution was localized to the cytoplasm in up to 10% of pancreatic ductal epithelial cells and was not detected in any other tissues examined.HepG2 cells overexpressing URG4 displayed increased growth in the absence of HBxAg. Flow cytometry analysis of URG4 transfected HepG2 cells confirmed that URG4 stimulated cell growth and promoted the entry of cells into S phase.