The Rho GTPases—Rho, Rac, and CDC42—are small GTP-binding proteins that regulate basic biological processes such as cell locomotion, cell division, and morphogenesis by promoting cytoskeleton-based changes in the cell cortex. These proteins are active when bound to GTP and can bind to and stimulate effector proteins, which in turn promote actin assembly and myosin-2-based contraction to pattern the cortex. However, recent evidence suggests that Rho GTPase activation and inactivation are often tightly coupled in space and time via signaling circuits and networks based on positive and negative feedback. This coupling allows Rho GTPases to self-organize, forming diverse spatio-temporal cortical patterns such as static clusters, oscillatory pulses, and traveling wave trains. The self-organization of Rho GTPases is crucial for cell function, enabling the formation of dynamic patterns necessary for processes like cell migration, phagocytosis, and cytokinesis. The Rho GTPase cycle, involving GTP binding, hydrolysis, and GDP-GTP exchange, is tightly regulated by GEFs and GAPs, which are essential for maintaining the spatial and temporal dynamics of Rho GTPase activity. The self-organization of Rho GTPases is further supported by the presence of feedback loops, which can be direct or effector-based, and are critical for generating and maintaining cortical patterns. These patterns are essential for various cellular processes, including polarized growth in yeasts, pulsed contractions in embryos, and traveling waves in cell division. The study highlights the importance of Rho GTPase dynamics in cell cortex patterning and the role of self-organization in enabling the complex and dynamic behaviors of cells.The Rho GTPases—Rho, Rac, and CDC42—are small GTP-binding proteins that regulate basic biological processes such as cell locomotion, cell division, and morphogenesis by promoting cytoskeleton-based changes in the cell cortex. These proteins are active when bound to GTP and can bind to and stimulate effector proteins, which in turn promote actin assembly and myosin-2-based contraction to pattern the cortex. However, recent evidence suggests that Rho GTPase activation and inactivation are often tightly coupled in space and time via signaling circuits and networks based on positive and negative feedback. This coupling allows Rho GTPases to self-organize, forming diverse spatio-temporal cortical patterns such as static clusters, oscillatory pulses, and traveling wave trains. The self-organization of Rho GTPases is crucial for cell function, enabling the formation of dynamic patterns necessary for processes like cell migration, phagocytosis, and cytokinesis. The Rho GTPase cycle, involving GTP binding, hydrolysis, and GDP-GTP exchange, is tightly regulated by GEFs and GAPs, which are essential for maintaining the spatial and temporal dynamics of Rho GTPase activity. The self-organization of Rho GTPases is further supported by the presence of feedback loops, which can be direct or effector-based, and are critical for generating and maintaining cortical patterns. These patterns are essential for various cellular processes, including polarized growth in yeasts, pulsed contractions in embryos, and traveling waves in cell division. The study highlights the importance of Rho GTPase dynamics in cell cortex patterning and the role of self-organization in enabling the complex and dynamic behaviors of cells.