Vacuolin-1 is a potent and cell-permeable inhibitor that blocks the Ca(2+)-dependent exocytosis of lysosomes and prevents the release of lysosomal content without affecting the process of resealing. Vacuolin-1 is also a potent and selective PIKfyve inhibitor, and inhibits autophagy by impairing lysosomal maturation via PIKfyve inhibition.