KRAS and colorectal carcinoma: K-ras activating point mutations occur in about 50% of human sporadic CRC cases and act by stabilising the active GTP-bound configuration, and so promote cellular transformation by constitutive activation of downstream effector pathways, including Raf kinases, phosphatidylinositol 3-kinases (PI3-K), and RalGDS family members [reviewed [6]].