Biological activities and molecular targets of the human papillomavirus E7oncoprotein

The human papillomavirus (HPV) E7 protein is one of only two viral proteins that remain expressed in HPV-associated human cancers. HPV E7 proteins sha re structural and functional similarities with oncoproteins encoded by othe r small DNA tumor viruses such as adenovirus EIA and SV40 large tumor antig en. The HPV E7 protein plays an important role in the viral life cycle by s ubverting the tight link between cellular differentiation and proliferation in normal epithelium, thus allowing the virus to replicate in differentiat ing epithelial cells that would have normally withdrawn from the cell divis ion cycle. The transforming activities of E7 largely reflect this important function.