P-Rex1, a guanine exchange factor that is overexpressed in breast cancer, is a convergence node for ErbB and CXCR4 signaling.

In a recent issue of Molecular Cell, Kazanietz and colleagues (Sosa et al., 2010) show that P-Rex1, a Rac1 GEF, is overexpressed in ER+ and/or ErbB2+ breast cancers, suggesting that P-Rex1 might be a convergence node downstream of these receptors and an attractive therapeutic target. Copyright Â