To demonstrate the roles of PIWI in NSCLC, real-time PCR, western blot and IHC were employed to assay the expression levels of the four PIWI homologs (PIWIL1, PIWIL2, PIWIL3 and PIWIL4) in NSCLC tissues and adjacent tissues. Here, PIWIL4 is linked to non-small cell lung carcinoma.