Figure 1.

Rho GTPases in lamellipodium-driven migration. In cells using lamellipodia to drive migration, cell migratory polarity is established by Cdc42, acting through the Par polarity complex and microtubules. Membrane protrusions at the front of cells include lamellipodia and filopodia. Cdc42 is the main GTPase contributing to filopodium extension, acting through mDia formins. Rac induces lamellipodium extension through the WAVE complex, which activates the Arp2/3 complex. Adhesions to the extracellular matrix form in lamellipodia, initially through Rac and its target PAK, among other proteins. Rho and ROCKs promote formation of larger, more persistent integrin-based adhesions. Actomyosin contraction in the cell body is important for driving the cell forward and for detachment of the back of the cell, and is mediated by Rho and ROCKs and/or Cdc42 and MRCKs.