EGFR and neoplasm: For EGFR sensitive mutation cases, EGFR-TKIs treatment cases, receiving second biopsy cases and T790M mutation cases (both HIF-1α level before treatment and after acquired resistance were analyzed for second biopsy cases and T790M mutation cases), there was no different HIF-1α expression among tumor stages (P = 0.320, 0.137, 0.510, 0.216, 0.547 and 0.207, respectively, Table 5).