PGE₂ production by MSCs is up-regulated in monocyte-MSC cocultures. PGE₂ levels were measured in culture SN of MSCs cultured alone (■) or with monocytes () induced to differentiate into DCs. PGE₂ was evaluated by ELISA assay performed on SN collected at 24, 48, and 72 hours of culture. Results are expressed as mean of PGE₂ levels measured in 7 independent experiments performed using different MSC populations. Data are expressed in pg/mL. **P < .01.