Fig. 2
From: Regulatory mechanisms of immune checkpoints PD-L1 and CTLA-4 in cancer
Regulatory mechanisms of PD-L1. PD-L1 expression is regulated at RNA level (inflammatory signaling, aberrant oncogenic signaling, regulation by miRNA, epigenetic regulation, mRNA stabilization), DNA level (genomic alteration, epigenetic regulation), and protein level (ubiquitination, phosphorylation, glycosylation, palmitoylation). Extracellular PD-L1 (exosome, soluble protein) and biomarkers also regulate PD-L1 expression.