These findings were consistent with previous cell line studies indicating that coculturing with HGF-secreting fibroblasts made EGFR-mutant lung cancer cell lines resistant to EGFR TKIs (23), and that ERBB3 activated the PI3K/AKT pathway in EGFR TKI sensitive — rather than resistant — NSCLC cell lines (21). This evidence concerns the gene PIK3CA and lung carcinoma.