In non-small cell lung cancer (NSCLC) cells, let-7 is inhibited by circ-CPA4 via its molecular sponge function, and the knockdown of circ-CPA4 inhibited cell growth, mobility and promoted cell death by downregulating the release of exosomal PD-L1, which promotes CSC-like activities and resistance of NSCLC cells to cisplatin [75]. The gene discussed is CPA4; the disease is non-small cell lung carcinoma.