PTGS2 and melanoma: In another study, ALDH3A1’s expression was determined by IHC in melanoma patients, along with the expression of programmed death-ligand 1 (PD-L1), and cyclooxygenase-2 (COX-2), while after overexpressing it in melanoma cultures, it was correlated with tumor stemness, epithelial to mesenchymal transition (EMT) markers, and PD-L1 expression [157].