Most stromal cells in NSCLC cultures showed no intrinsic expression of ABCB1, ABCC1, or ABCG2 and showed only a slight increase in expression of these MDR markers after treatment with erlotinib or nintedanib, which was not significant, indicating that stromal cells do not take part in the development of MDR to tested TKIs. This evidence concerns the gene ABCG2 and non-small cell lung carcinoma.