Tyrosine Hydroxylase and Monoamine Oxidase-A Activity Increases in Differentiating Human Neuroblastoma After Elimination of Dividing Cells

SY5Y neuroblastoma cells were treated with retinoic acid to induce differentiation of neuroblast-like cells and with aphidicolin (an inhibitor of DNA polymerase) to eliminate the flat cells present in the long-term cultures and masking some of the biochemical developmental changes. Catecholaminergic enzyme (tyrosine hydroxylase and monoamine oxidase-A) activity was consistently increased with development and the increase was significantly greater after aphidicolin-induced elimination of dividing, non-neuronal cells.