The Ca2+-dependent exocytosis of enlargeosomes is greatly reinforced by genistein via a non-tyrosine kinase-dependent mechanism

Studies carried out by immunofluorescence, patch-clamping and FM dye fluorescence consistently showed that the Ca2+-induced exocytosis of enlargeosomes, specific vesicles expressed by many cell types, is strongly reinforced by pre-treatment of the cells with genistein, a wide spectrum blocker of tyrosine kinases, which also induces many additional effects. Various other blockers of tyrosine kinases, however, were ineffective, and the same occurred with drugs mimicking most of the rapid, non-tyrosine kinase-dependent effects of genistein. The reinforcement of enlargeosome-regulated exocytosis, therefore, is a new effect of genistein and a peculiar property of the enlargeosome exocytosis, not shared by analogous processes.