In comparison to miR-21+/+ mice, PD-L1 positive cells (Figure 4(c)) and the positive rate of Ki67 protein expression (Figure 4(d)) were decreased, and apoptosis of BC cells (Figure 4(e)) was increased in the miR-21+/+ mice treated with radiotherapy or anti-PD-L1 antibody alone. Here, MKI67 is linked to breast cancer.