Interestingly, we found that circ-CPA4 also positively regulated exosomal PD-L1 expressions by silencing let-7 miRNA in the supernatants of NSCLC cells, hence the NSCLC cells deficient of circ-CPA4 were next co-cultured with CD8+ T cells. The gene discussed is CD8A; the disease is non-small cell lung carcinoma.