Jing-Po Li (Whitehead Institute for Biomedical Research, Cambridge, Mass.): "Most malignant diseases involve a multistage process. This often features an early phase of abnormal proliferation of the affected tissues, and a late phase, during which additional genetic changes accumulate and true malignancy emerges. The erythroleukemia induced by the Friend virus in mice offers a good model to study the oncogenic process in certain specific tissues.
"This paper shows that a viral-encoded protein, gp55, can activate the abnormal proliferation of the infected hematopoietic cells by binding to the cellular receptor for erythropoietin. This may be the key event in triggering the prolonged proliferation of the erythroid cells after virus infection. Similar instances may exist in other types of malignancies in which a viral protein, or some other cancer-causing substance, can interact with one of the growth factor receptors. This results in an uncontrolled proliferation of certain tissues containing the receptor, which ...
