DDB1 and liver cancer: The Cul4A gene located on human chromosomes q13 and q34 is amplified in liver cancer, suggesting that increased expression of CUL4A may promote carcinogenesis.43DNA binding protein 1 (DDB1) and E3 ligase Cullin 4 (CUL4) interact with HBx, forming HBx–DDB1–CUL4 E3 ligase complex, and preserve viral protein against UPS.41, 44