BDNF and neuroblastoma: PC12 cells derive from a rat pheochromocytoma and can be differentiated to chatecholaminergic neuron-like cells in low serum and addition of nerve growth factor (NGF), while human neuroblastoma cell line SH-SY5Y can be differentiated to chatecholaminergic, but predominantly noradrenergic, nerve cells under low serum concentrations in the presence of either all-trans-retinoic acid (ATRA) or brain-derived neurotrophic factor (BDNF).