The ras family (H-Ras,K-Ras,and N-Ras) are proteins that act as GDP/GTP-regulated binary switches that reside at the inner surface of the plasma membrabe and act to relay extracellular ligand-stimulated signals to cytoplasmic signaling cascades. However ,oncogenic forms of Ras lose their responsiveness to growth receptor tyrosine kinases and constitutively active cascades of serine threonine kinases that controll cell proliferation,inhibit appotosis,and increase protein translation.