This same approach was applied to dissect the heterogeneity of T cell subsets to address several biological questions in particular related to “tumor immunity.” The role of T cells in cancer has been extensively studied in the past few years and CD8+ T cells and CD4+ T regulatory cells have been broadly described to inhibit or promote tumor progression, respectively, in several types of cancer (35, 36). The gene discussed is CD8A; the disease is neoplasm.