The original KRAS diagnostic, which assesses mutations only in codons 12 and 13 in exon 2 of the protein, improves the response rate of the corresponding combination EGRF inhibitor/irinotecan therapy in second line colon cancer from 10% in unselected patients to a still relatively meager 35% for the KRAS exon 2 wild type group [58]. The gene discussed is KRAS; the disease is malignant colon neoplasm.