NPY and neuroblastoma: Since NPY increases the intracellular Ca2+ levels via mobilization of Ca2+ from the endoplasmic reticulum in neuroblastoma cells [21], and activation of phospholipase C-beta (PLCβ) is known to mobilize Ca2+ from this cell compartment [24], we tested whether the NPY-induced increase of intracellular Ca2+ is mediated by this pathway.