CD8A and neoplasm: TUNEL assay confirmed apoptotic events in these perimetastatic areas and showed an increased rate of apoptotic CD8+ cells during tumor growth: CD8+/TUNEL day 10: 5.6 ± 2.9%, day 15: 13 ± 4.7%, day 20: 20 ± 3.4% (day 20 shown in Figure 6b).