PER2 and cancer: To assess whether T cells mediate the tumor growth inhibition observed in Per1–/–Per2–/– mice, as well as to exclude the possibility that Per1–/–Per2–/– mice reject the MC38 cancer cells due to their expression of Per1 and Per2 genes, we injected cancer cells into WT or Per1–/–Per2–/– mice in which T cells were depleted by CD4 and CD8 antibodies (Supplementary Figure 1B).