Squamous cell differentiation markers, cytokeratin 5/6, p40, and p60 were diffusely positive in SCC, but extremely limited in NEC (Fig. 4E, F) Regard to tumor suppressor proteins (Fig. 6A–F), both components revealed diffusely, generally, and focally immunoreactivity toward Rb, p16, and p53, respectively. The gene discussed is RB1; the disease is neuroendocrine carcinoma.