A synergistic effect of OP/BMP morphogens in combination with GDNF/NGF neurotrophic factors in promoting the survival or growth, or inhibiting the death or degeneration, of mammalian cells, particularly neural cells, which express OP/BMP-activated serine/threonine kinase receptors and GDNF/NGF-activated tyrosine kinase receptors, is disclosed. Also disclosed are new methods for the in vivo and in vitro treatment of such cells, including in vivo treatments for mammals afflicted with, or at imminent risk of, damage or injury to such cells, as well as new pharmaceutical preparations for such in vivo and in vitro treatments.
