EGFR and non-small cell lung carcinoma: Importantly, DNA analyses from PC‐9GR ruled out the link between the development of acquired resistance to Gefitinib of PC‐9GR cells and secondary EGFR T790M mutation, which is the most common mechanisms of acquired TKI resistance in NSCLC (Yun et al, 2008; Sequist et al, 2011).