Expression of v-SNAREs in synaptobrevin 2−/−, VAMP-3−/−, and VAMP-8−/− mast cells. Whole-cell lysates from 4 × 106 mast cells derived from synaptobrevin 2−/−, VAMP-3−/−, and VAMP-8−/− mice (and corresponding wild-type and heterozygous littermate controls) were analyzed by reducing SDS/PAGE and immunoblotting by using antibodies recognizing synaptobrevin 2, VAMP-3, VAMP-7, VAMP-8, SNAP-23, and β-tubulin.