One study showed that COX-2 and PD-L1 were expressed in both primary melanoma lesions and non-matching lymph node metastases and that the inhibition of COX-2 activity by celecoxib downregulated PD-L1 expression in both BRAFV600E A375 and NRASQ61R SK-MEL-2 melanoma cell lines (32). This evidence concerns the gene PTGS2 and melanoma.