One reason for this could be that KRAS has no direct interaction with antibody binding at the antigen site and therefore it is prudent to investigate the expression of other members of the HER family, which have been shown to activate the downstream pathways, via heterodimerisation and cross-talk, and drive the tumourigenesis of colorectal cancer in these patients [17]–[19]. Here, KRAS is linked to colorectal cancer.