CD8A and neoplasm: Although we saw no effect on the frequency of αβ T cells (Supplementary Figure 5A), we observed evidence of increased T cell activation: E0771 tumors from Ptpn6fl/flERT2-cre mice contained a higher frequency of activated, antigen-experienced (CD44hi) CD4+ and CD8+ T cells, and an increase in the ratio of effector CD4+ and CD8+ T cells to Tregs (Figure 5D), consistent with an anti-tumor response.