Regulation of actin cytoskeleton by Rho GTPases
Ras homolog gene family, member A ( RhoA ) downstream effector Rho-associated, coiled-coil containing protein kinase ( ROCK ) directly phosphorylates LIM domain kinases 1 and 2 ( LIMK1 and LIMK2 ) that in turn phosphorylates Cofilin. Cofilin exhibits Actin -depolymerizing activity followed by reorganization of the Actin cytoskeleton .
The activated ROCK also subsequently phosphorylates and inactivates the Myosin light chain phosphatase ( MLCP )  that attenuates Myosin light chains ( MELC ) (myosin light chains) and Myosin light chain regulatory ( MRLC ) phosphorylation .
Ras-related C3 botulinum toxin substrate 1 ( Rac1 ) downstream effector P21 protein-activated kinase 1 ( PAK1 ) directly phosphorylates LIMK1 , inhibits MLCK , activates MRLC  and ARP2 actin-related protein 2 and 3 ( Arp2/3 ) complex . Arp2/3 complex nucleates new Actin filaments from the sides of preexisting filaments. . Also, WAS protein family member 1 ( WAVE ) plays a critical role downstream of Rac in that it regulates the Actin cytoskeleton required for membrane ruffling. WAVE share function as an inducer of Actin reorganization through profiling .
Cell division cycle 42 ( CDC42 ) initiates Wiskott-Aldrich syndrome ( WASP )/ Arp2/3 nucleation of Actin . Recruitment of factors, including Profilin, by WASP stimulates cellular Actin -based motility .