The small GTPases Ras, the products of the ras proto-oncogenes, consist of three isoforms, H-Ras, K-Ras and N-Ras, in mammals and are frequently activated by amino acid substitution mutations such as G12V and Q61L in a wide variety of human cancers, making them some of the most promising targets for anti-cancer drug development1. This evidence concerns the gene KRAS and cancer.