RhoA is one of the more extensively studied members of the Rho family of small 
GTPase where it is most readily recognized for its contributions to actin-myosin 
contractility and stress fiber formation. Accordingly, RhoA function during cell 
migration has been relegated to the rear of the cell where it mediates 
retraction of the trailing edge. However, RhoA can also mediate membrane 
ruffling, lamellae formation and membrane blebbing, thus suggesting an active 
role in membrane protrusions at the leading edge. With the advent of 
fluorescence resonance energy transfer (FRET)-based Rho activity reporters, RhoA 
has been shown to be active at the leading edge of migrating cells where it 
precedes Rac and Cdc42 activation. These observations demonstrate a remarkable 
versatility to RhoA signaling, but how RhoA function can switch between 
contraction and protrusion has remained an enigma. This review highlights recent 
advances regarding how the cooperation of Rho effector Rhotekin and S100A4 
suppresses stress fiber generation to permit RhoA-mediated lamellae formation.