Calcium-dependent and calcium-independent exocytosis.

A large body of evidence supports the concept that calcium (Ca2+) plays a pivotal role in the control of exocytosis. However, recent experiments suggest that a rise in intracellular Ca2+ does not necessarily trigger secretion, and also that secretion can occur independently of cytosolic free calcium levels. This article briefly summarizes the early evidence that has formulated the role of Ca2+ in secretion, and then examines some of the recent evidence suggesting a Ca2+-independent mechanism of exocytosis.