KRAS and colorectal cancer: For many years, mutations in a relatively limited number of key genes including APC (adenomatous polyposis coli), Kirsten-Ras (K-Ras) and p53 were considered to have a central role in the development of colorectal cancer, whereas more recent data have identified an increasingly complex network of genes and mutations associated with disease pathogenesis (Fearon and Vogelstein, 1990; Smith et al, 2002; Leslie et al, 2003; Conlin et al, 2005; Suehiro et al, 2008), progression, survival and treatment response (Soong et al, 2000; Smith et al, 2002; Lièvre et al, 2006; Kato et al, 2007).