In addition, signal transducer and activator of transcription 3 (STAT3), mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathways activate the expression of PD-L1 receptor, which contributes to melanoma immune escape (25) (Figure 1). This evidence concerns the gene STAT3 and melanoma.