NGF and hereditary pheochromocytoma-paraganglioma: Toward this end the neuroblastoma, wild type SH-SY5Y and SH-SY5Y-APP cell lines were incubated with all-trans retinal for 6 days, while the pheochromocytoma wild type PC12 and PC12-htau cell lines were incubated with NGF for 7 days, to enable differentiation to neuron-like cells.