Small GTPases are a family of proteins that act as molecular switches in cells. They regulate various cellular processes, including growth, differentiation, and movement, by cycling between an active and inactive state. When bound to guanosine triphosphate (GTP), they are active, and when they hydrolyze GTP to guanosine diphosphate (GDP), they become inactive. These proteins play crucial roles in signaling pathways, often interacting with other proteins to transmit signals within the cell. Small GTPases are involved in processes such as cell division, cytoskeletal dynamics, and vesicle trafficking, making them essential for maintaining cellular function and responding to external stimuli.