Figure 7: Natural killer (NK) cells cytotoxic assays. Freshly isolated NK cells of 4 rats were incubated with fibrosarcoma cells silenced for RT1-A expression at different levels at an effector : target (E : T) ratio 5 : 1 for 6 h. Cell lysis was detected by flow cytometry after staining with 7-amino-actinomycin D. Statistically significant differences are shown with asterisks (*** ).