In contrast to the discovered unfavorable effects of CD13 protein presence in a subgroup of NSCLC, the analysis of CD13 mRNA expression for all lung cancer patients (p = 0.00038; HR = 0.8; n = 1926 patients; all tumor histologies) on the basis of Affymetrix microarray data demonstrated a positive prognostic effect. The gene discussed is ANPEP; the disease is non-small cell lung carcinoma.