Next, the result of RT-qPCR, Western blot and IHC assays furtherly revealed that ERRα mRNA and protein level was significantly upregulated in PC-9/GR, H1975, PC-9/OR cells and xenograft tumors compared with PC-9 cells, suggesting enhanced ERRα expression was related to NSCLC progression and development of EGFR-TKIs resistance (Fig. 2a-c). Here, EGFR is linked to non-small cell lung carcinoma.