Integrins make a choice

Signaling researchers have only a few factors with which to explain a whole lot of biology. On page 407, Goel et al. describe how two integrin variants channel the actions of a single factor, insulin-like growth factor (IGF), into two distinct pathways that induce either adhesion or proliferation.

The β1A integrin variant was known to be associated with proliferation and the β1C variant to inhibit it. IGF and its receptors had also been found to enhance adhesion through β1 integrins.

Goel et al. find that, in cells with β1A integrin, IGF binding to its receptor induces formation of a ternary complex of integrin, IGF receptor and the downstream signaling protein IRS-1. The resultant boost in cell proliferation is, however, prevented by expression of the β1C integrin. A short insertion in the cytoplasmic tail of...