EGFR and non-small cell lung carcinoma: As the transforming growth factor (TGF)-β1 is a strong inducer of the EMT [12,13] and a positive regulator of the CSC phenotype [14,15], and a TGB-β1-induced EMT has been previously correlated to EGFR-TKI resistance in NSCLC cells [16,17], we measured TGF-β1 expression in the GR cells.