RIP was used to verify the binding relationship between miR-214-5p and PSMA3-AS1 or PD-L1 [22 (link)]. RIP assay was conducted with an EZMagna RIP kit (Merck KGaA). Cell lysates were treated with magnetic beads conjugated to Ago2 antibody (Abcam) or control IgG antibody (Abcam) in RIP buffer. All precipitated RNAs were examined by RT-qPCR.