STAT3 and lung cancer: Previous studies have demonstrated that EGFR‐TKI dramatically altered microRNA expression profiles in NSCLC cells.25, 44 In turn, altered microRNA expression associated strongly with TKI response by modulating crucial signalling pathway.45 Here, we reported a mechanism by which EGFR‐mutant lung cancer cells escaped the gefitinib treatment of TKI via over‐activation of STAT3 through miR‐206 down‐regulation.