Moreover, in A549GSC and H1650GSC cells, treatment with atRA was shown to dramatically lower the IC50 values for gefitinib, an ATP-competitive EGFR tyrosine kinase inhibitor used in non-small cells lung cancer (NSCLC) treatment, and the high expression of ALDH 1 family member A1 (ALDH1A1) and CD44 [256]. This evidence concerns the gene ALDH1A1 and non-small cell lung carcinoma.