Fig 4. Blockage of gefitinib withdrawal induced reverse EMT, and the forced expression of Snail and Slug inhibited the regain of gefitinib sensitivity.

(A) The vectors pLex, pLex-Slug and pLex-Snail were introduced into the PC9-GR and PC9-WGR cells at different passages. The protein levels of EMT biomarkers were examined by Western blot. (B) The vectors pLex, pLex-Slug and pLex-Snail were introduced into the HCC827-GR and HCC827-WGR cells at different passages. The protein levels of EMT biomarkers were examined by Western blot. (C) Parental, GR and WGR PC9 cells at different passages were treated with gefitinib at the indicated concentrations for 72 hours, and the relative cell viability was determined by MTT assay. The IC₅₀ values at each passage after gefitinib withdrawal were determined and plotted. (D) Parental, GR and WGR HCC827 cells at different passages were treated with gefitinib at the indicated concentrations for 72 hours, and the relative cell viability was determined by MTT assay. The IC₅₀ values at each passage after gefitinib withdrawal were determined and plotted.