Mutations in the KRAS gene are the most common cancer-driving mutations in all cancers; they occur in 20% of lung cancers and 40% of colon cancers. KRAS-mutant cancers are aggressive and do not respond well to current treatments. Although the importance of KRAS mutations in cancer has been known for over 30 years, scientists have so far not succeeded in developing a drug targeting them. Now researchers have located a previously undetected 'pocket' on a certain mutated form of the KRAS protein. The mutation, called KRAS(G12C), occurs in 7% of lung cancer and 9% of colorectal cancer patients. The researchers then created molecules that bind to the 'pocket' and inhibit the mutant KRAS, but not normal KRAS protein. They hope to develop these compounds into drugs against KRAS-mutant cancers.