MiR-let-7c sensitizes H1975 (EGFR L858R/T790M double mutation) and HCC827-T790M NSCLC cells (T790M mutation acquired by continuous exposure to erlotinib and MET inhibitor) to osimertinib by decreasing tumor cell proliferation and invasion in addition to reversing EMT through increased E-cadherin and decreased ZEB1. The gene discussed is EGFR; the disease is neoplasm.