CD274 and gastric cancer: MiR-214-3p can inhibit the expression of PD-L1 by targeting its 3′UTR, but lncRNA urothelial carcinoma associated 1 (UCA1) can up-regulate PD-L1 expression through inhibiting miR-214-3p, which promotes gastric cancer (GC) cell proliferation and migration and inhibits apoptosis, so miR-214-3p can be used as potential new therapeutic target of GC treatment (Wang et al., 2017; Sun, Zhang & Zhang, 2019; Song, Park & Uhm, 2019).