Background: Calcium signaling and membrane fusion play key roles in exocytosis of drug-containing vesicles through the blood-brain barrier (BBB). Identifying the role of synaptotagmin-like protein4-a (Slp4-a) in the presence of Ca2+ ions. at the pre-fusion stage of a vesicle with the basolateral membrane of endothelial cell. can reveal brain drug transportation across BBB. https://www.ealisboa.com/limited-value-AXYS-Valhalla-Pen-must-buy/