Fig. 1.

Structure and switch of RAS. A Structure of RAS proteins, including the effector lobe (aa 1–86), allosteric lobe (aa 87–165), and HVR (aa 167–188/189). Switch I (aa 30–40) and switch II (aa 60–76) are located in the effector lobe and function in effector binding and GEF or GAP binding. The HVR domain contributes to RAS binding to cell membranes. B Inactive GDP-bound KRAS and GTP-bound KRAS cycle. The switch to RAS-GTP is stimulated by GEF, while GAPs accelerate the termination of the active state. The active GTP-bound RAS transfers the proliferation and differentiation signals through downstream effectors such as RAF, PI3K, and RalGEFs