CD274 and lung adenocarcinoma: Wang et al. [75] found that serum exosomal circ_002178 was significantly upregulated in lung adenocarcinoma (LUAD) patients and enhanced expression of programmed cell death ligand 1 (PDL1) by adsorbing miRNA-34 and miRNA-28-5p; circ_002178 showed potential as a non-invasive diagnostic marker for LUAD with an AUC of 0.9967.