However, in our analysis of the exonic regions encoding the first 100 amino acids of KRAS in 110 surgically resected early-stage non-small-cell lung cancers, we have found 18 mutations, and all were in either codon 12 or codon 13, encoded by exon 2 (W. Pao, R. Wilson, H. Varmus, unpublished data). The gene discussed is KRAS; the disease is non-small cell lung carcinoma.