hASH1, Chromogranin A, Synaptophysin and CD56 expression were examined in lung tumor specimens (lung inflammatory pseudotumor, squamous cell carcinoma, adenocarcinomas, large cell carcinoma, typical carcinoids, atypical carcinoids, large cell neuroendocrine carcinomas and small cell lung carcinoma and corresponding normal lung specimens) using immunohistochemistry (S-P method). The gene discussed is ASCL1; the disease is squamous cell carcinoma.