CD4 and non-small cell lung carcinoma: To further investigate the association between APE1 expression and the density of tumor-infiltrating CD4+ T cell subsets and confirm the results stemmed from the GEO datasets, APE1 expression and CD4+ T cell infiltration were divided into high- and low-score groups separately according to the IHC staining in the other cohort comprised of 108 NSCLC patients.