KRAS and colorectal neoplasm: Previous analyses of K-Ras mutations in human tumours have consistently focussed on single-point mutations in codons 12, 13 and 61, where mutation has been shown to result in reduced Ras GAP GTPase activity, locking the protein in the active Ras-GTP conformation (Ellis and Clark, 2000), although additional mutations at codons 19, 22 and 146 have been described in single colorectal tumour case reports (Orita et al, 1991; Miyakura et al, 2002; Akagi et al, 2007).