Furthermore, we demonstrated that RNase1 increased the expression of immune inhibitory checkpoint proteins (Figure 1H,I) and compromised CD8+ T‐cell cytotoxicity in vitro (Figure 2H–J), and in vivo experiments demonstrated that RNase1 inhibited CD8+ T‐cell activity, thereby promoting breast cancer growth (Figure 4G–I). This evidence concerns the gene RNASE1 and breast cancer.