The article by Catherine D. Nobes and Alan Hall explores the role of small GTPases, specifically Rho, Rac, and Cdc42, in controlling cell polarity, protrusion, and adhesion during cell movement. They use an in vitro wound healing assay with primary embryo fibroblasts to analyze the contributions of these GTPases. The study reveals that Rac is essential for the protrusion of lamellipodia and forward movement, Cdc42 is required to maintain cell polarity, including the localization of lamellipodial activity to the leading edge and the reorientation of the Golgi apparatus, and Rho is necessary for maintaining cell adhesion. Additionally, Ras is found to regulate focal adhesion and stress fiber turnover, which is essential for cell movement. The authors conclude that the signal transduction pathways controlled by these four small GTPases cooperate to promote cell movement.The article by Catherine D. Nobes and Alan Hall explores the role of small GTPases, specifically Rho, Rac, and Cdc42, in controlling cell polarity, protrusion, and adhesion during cell movement. They use an in vitro wound healing assay with primary embryo fibroblasts to analyze the contributions of these GTPases. The study reveals that Rac is essential for the protrusion of lamellipodia and forward movement, Cdc42 is required to maintain cell polarity, including the localization of lamellipodial activity to the leading edge and the reorientation of the Golgi apparatus, and Rho is necessary for maintaining cell adhesion. Additionally, Ras is found to regulate focal adhesion and stress fiber turnover, which is essential for cell movement. The authors conclude that the signal transduction pathways controlled by these four small GTPases cooperate to promote cell movement.