To further understand the difference in Hh signaling pathway activity between EGFR-TKI-sensitive and -resistant NSCLCs, expression of GLI1, ABCG2, Snail, and E-cadherin was assessed by IHC in four NSCLC tissues that contained the EGFR exon 19 deletion or the L858R sensitive mutation, four tissues that contained the EGFR T790M secondary mutation, and four tissues that contained the KRAS mutation (Fig 4). This evidence concerns the gene KRAS and non-small cell lung carcinoma.