CD8A and neoplasm: Fluorescence activated cell sorting (FACS) analysis was performed on these excised colon tumours and showed that these MC38 tumours had greater infiltration of CD8+ CD25+ cells compared to CT26 tumours (16.12 ± 4.14 vs. 5.14 ± 1.09, p < 0.002, Figure 5C), whereas no significant difference was observed for CD4+ CD25+ cells (52.82 ± 5.31 vs. 50.