Epidermal growth factor modulates release of arachidonic acid from embryonic cells.

The calcium ionophore A23187 stimulates release of free [3H]arachidonic acids from radiolabeled cultures of MEPM cells which are growing, but not from those which are confluent. However, when confluent MEPM cells are pretreated with EGF or PMA, release of [3H]arachidonic acids does occur in response to A23187. Since neither EGF nor PMA themselves stimulate release of [3H]arachidonic acids from these cells, but do activate protein kinase C, these data support the hypothesis that protein kinase C modulates the activities of phospholipid hydrolases in MEPM cells.