KRAS and colorectal neoplasm: K-Ras mutations have been reported in between 25 and 37% of colorectal tumours (Smith et al, 2002; Yuen et al, 2002; Calistri et al, 2005; Oliveira et al, 2007), with mutations most commonly described in codons 12 and 13 (Bos, 1989; Smith et al, 2010).