In this pathway, PIK3CA, KRAS and BRAF genes are frequently activated by mutations in various tumour types, including CRC (Samuels et al, 2004; Oikonomou and Pintzas, 2006; Cardoso et al, 2007; Kato et al, 2007) with frequencies of 10–30% (Samuels et al, 2004; Velho et al, 2005; Kato et al, 2007; Barault et al, 2008; Nosho et al, 2008; Ogino et al, 2009b), 30–40% (Vogelstein et al, 1988; Andreyev et al, 1998; Cardoso et al, 2007) and 5–22% (Yuen et al, 2002; Cardoso et al, 2007), respectively. Here, KRAS is linked to colorectal carcinoma.