Russo AJ, Mathiowetz AJ, Hong S, Welch MD, and Campellone KG (2016).  Rab1 recruits the actin nucleation machinery but limits filament assembly during membrane remodeling.  Mol Biol Cell. 27(6):967-978. (Cover)

Small G-proteins are molecular switches that signal to the actin cytoskeleton to control the shape and movement of cells and their organelles. In the article on p. 967 of this issue of MBoC, Russo et al. report that the small G-protein Rab1 binds to the actin nucleation factor WHAMM to stimulate the tubulation of endomembranes. Rab1 is able to recruit WHAMM to membranes in cells but unexpectedly limits its actin nucleation activity in vitro. This image depicts numerous tubular membranes radiating from the center of a cell coexpressing fluorescently tagged versions of Rab1 (red) and WHAMM (green). Actin filaments are shown in magenta and nuclear DNA in blue. (Image: Ken Campellone, University of Connecticut)