p40 and TTF-1 immunoexpression in lung cancer. Cell blocks obtained from poorly differentiated SCC (a–c) and ADC (d–f). The SCC shows strong nucleus positivity for p40 (b) and negativity for TTF-1 (c) while the ADC has the opposite p40 (e) and TTF-1 (f) immunoexpression. HE = Hematoxylin and eosin stain.