To explore the clinical significance of PPA1 in lung carcinoma, we performed the immunohistochemical analysis to detect the expression of PPA1 with a PPA1-specific antibody in frozen primary lung carcinoma samples (n = 185, contained 62 adenocarcinoma, 93 SCC, 9 adeno acathnoma and 21 SCLC) and normal lung tissues (n = 10) (Fig. 1a). This evidence concerns the gene PPA1 and small cell lung carcinoma.