Normal stimulation of the synthesis, phosphorylation and DNA binding activity of c-Fos and Zif268 proteins by nerve growth factor is not sufficient to mediate neuronal differentiation of PC12 cells.

Early-response genes (ERGs) are rapidly induced by nerve growth factor (NGF) in the PC12 rat pheochromocytoma cell line. To analyze the possible role of Ras and ERGs in neuronal differentiation, experiments were carried out to study the involvement of Ras proteins in the NGF-stimulated expression of two ERG-coded proteins (c-Fos and Zif268) implicated in NGF signaling. Using PC12 subclones expressing the dominant negative Ha-Ras Asn-17 protein, NGF-induced expression, phosphorylation and DNA-binding of these ERG products were found to be not sufficient to convey the biological response of PC12 cells to NGF.