GTPases are a family of enzymes that play a crucial role in cellular signaling and regulation. They bind and hydrolyze guanosine triphosphate (GTP), a molecule that provides energy for various cellular processes. When GTP is bound, GTPases are in an active state, allowing them to interact with other proteins and influence cellular functions. These enzymes act as molecular switches, toggling between an active and inactive form. The activity of GTPases is essential for processes such as cell growth, differentiation, and movement. Examples of GTPases include Ras, Rho, and Rab, each involved in specific signaling pathways within the cell.