When rat pheochromocytoma PC12 cells, which had differentiated into neuron-like cells following culture with nerve growth factor, were activated with glutamate, approximately 40% of their type II phospholipase A 2 (PLA 2 ) was released into the extracellular medium. Glutamate-stimulated secretion of dopamine from PC12 cells was suppressed by type II PLA 2 inhibitors. Exogenous type II PLA 2 added alone directly elicited release of dopamine from PC12 cells. Thus released type II PLA 2 may be involved in the regulation of neurotransmitter exocytosis by PC12 cells.