Immunohistochemistry. In normal tissue, only TSC1 is expressed in bronchus epithelia but not in alveolar surface cells (A). P-mTOR and p-tuberin were not detected in normal tissue (B, C). TSC1 was expressed in more than 50% of AC (D) and SCC (G) in contrast to 14% of SCLC (J). P-TSC2 was weakly expressed in 16.3% of AC (E), 6.5% of SCC (H) and 4.7% of SCLC (K). P-mTOR expression was found either in the cytoplasm or in nuclear position (F, I, L). Nuclear p-mTOR staining was found in 22.8% of AC (F), 35.5% of SCC (I) and 16.3% of SCLC (L). Cytoplasmic labeling of p-mTOR was found in 21.8% of AC (F) and 9.7% of SCC (I), but not in SCLC (L) specimens. Figures A-C: normal lung, D-F: AC, G-I: SCC, J-L: SCLC.