The above cellular results were also validated in vivo, and the results showed that knock-down of circ-CPA4 inhibited Cyclin D1 and Bcl-2 expressions, while increased the expression levels of Bax in mice tumor tissues, which were reversed by downregulating let-7 miRNA or upregulating PD-L1 (Fig. S1A-C). The gene discussed is CD274; the disease is neoplasm.