PTGS2 and major depressive disorder: Moreover, TGFB is known to play a neuroprotective role, especially in neurodegenerative disorders [32] as well as stimulate prostaglandin-endoperoxide synthase 2 (PTGS2; cyclooxygenase-2—COX-2) encoded by the PTGS2 gene, which is associated with depression etiology and progression [33,34].