Figure 2.

Simplified model illustrating the oncogenic properties of hepatitis B virus X protein and hepatoma upregulated protein in human liver cancer. In this cycle of gankyrin/MDM2-enhanced p53 degradation, HURP reduces MDM2-mediated ubiquitination of gankyrin, leading to accumulation of gankyrin in both normal and tumorigenic cells. Downstream effects of HURP appear to include malignant cell transformation and prevention of apoptosis induced by chemotherapeutic drug, processes which may in turn lead to the development of a chemoresistant cellular phenotype. HBx: Hepatitis B virus X protein; HURP: Hepatoma upregulated protein.