Cancer-causing motifs

A conserved activation motif identified in the envelope (Env) protein of murine mammary tumor virus (MMTV) can drive transformation of mammary epithelial cells, according to Katz et al. on page 431. The ability of this motif to transform cells single-handedly suggests that viral infection may be an important and previously unrecognized trigger for breast cancer.

The motif in question is the immunoreceptor tyrosine kinase–activating motif (ITAM). These conserved motifs are usually found in immune cells and, when phosphorylated, serve as docking sites for the assembly of proteins that signal the activation and differentiation of the cell. They have also been found in proteins from some oncogenic viruses such as Epstein Barr virus and Kaposi's sarcoma virus, but what role these motifs play in the transformation process has remained unexplored.

Katz and...