PTGS2 and neoplasm: Another study showed that RARβ2′s tumor suppressor function may be linked to its ability to decrease COX-2 expression, which plays a role in carcinogenesis and metastasis, and 13 cis-RA mediated activation of RARβ2 suppressed COX-2 expression, implying that COX-2 inhibition is dependent on RARβ2 expression.