SYT5 and neuroblastoma: By this we were able to document for the first time an interaction of polyclonal antisera directed to both HPy and CJe with the human synaptic calcium sensor synaptotagmin 5 (Syt5), and could correlate this interaction in SiMa human neuroblastoma cells to functional changes such as a diminished capability to respond to acetylcholine (ACh) with intracellular Ca++-transients, and a diminished rate of ACh-dependent vesicle recycling.