CD274 and renal cell carcinoma: Given that PD-L1 levels in RCC cells could be upregulated by miR-224-5p through inhibition of cyclin D1 expression, whether this mechanism could render RCC cells resistant to T cell-mediated toxicity was further investigated by conducting T cell killing assays, as shown in Figure 8A. Human peripheral blood mononuclear cells (PBMC) were isolated from fresh whole blood of healthy volunteers, and T cells were activated then co-incubated with 786-O and OS-RC-2 cells transfected with miR-224-5p or NC mimics/inhibitors.