For a comprehensive view of the tumor-infiltrating T cell landscape, the markers CD3, CD8, CD4, Programmed Cell Death Protein (PD)-1, granzyme B (GrzB) and Forkhead-Box-Protein P3 (FoxP3) were employed in addition to 4′,6-Diamidin-2-phenylindol (DAPI) nuclear staining (figure 2A, online supplemental figure 2a). The gene discussed is PDCD1; the disease is neoplasm.