A. Representative IHC images of normal or tumor lung tissues. Paraffin sections from tissue microarrays were immunostained with anti-HO-1 and anti-Nrf2 antibodies (brown) and counterstained with hematoxylin (blue). Tumor cores of 13 and 14 different patients were present on the TMA1 (HO-1) and TMA5 (Nrf2), as well as adjacent normal lung tissue cores. There was strong brown staining in tumor lung tissues, but significantly lighter staining in normal tissues (magnification, x400; Bar = 50 μm). Immunohistochemistry analysis of HO-1 and Nrf2 protein levels in normal and tumor lung specimens of different histological types and different stages are shown in B and C. Immunoreactivity is scored as the percentage of positive cells (0–3) multiplied by the intensity of cellular staining (0–3). HO-1 and Nrf2 expression scores in all tissues are shown in D and E. HO-1 and Nrf2 expression patterns are significantly increased in lung tumor tissues. Data are derived from two independent experiments and presented as means ± SEM in the scatter graphs. *p < 0.05, **p < 0.01, ***p < 0.001 vs. the human lung normal tissue by Student’s t-test.