Somatic mutations in the TK domain of the EGFR gene, including in-frame deletions in exon 19 and the point mutations L858, G719X, and L861Q, are associated with increased sensitivity to EGFR tyrosine kinase inhibitors (TKIs) and are present in 10~30% of patients with nonsmall cell lung carcinoma (NSCLC), depending on ethnic origin. Here, EGFR is linked to non-small cell lung carcinoma.