In the non-tumor mice, cell phenotyping by flow cytometry revealed that the gated CD4+ T cell population was significantly higher in circulating blood and spleen tissues (2.0- and 1.4-fold increases, respectively), whereas the CD8+ T cell population was significantly higher only in the spleen tissues (1.6-fold increase) of Per1/2−/− mice compared to wild-types (Figures 3C-3D). The gene discussed is PER1; the disease is neoplasm.