The effects of the protein kinase inhibitor K-252a on the in vitro survival of different populations of chick embryonic neurons were tested. Following dissociation from the corresponding ganglia by trituration, the neurons were cultured on laminin-coated dishes in both the presence and absence of their respective neurotrophic factor. K-252a alone promoted long-term neuronal survival of dorsal root ganglion (DRG) and ciliary ganglion (CG) neurons in a dose-dependent fashion. No such effect was seen with sympathetic ganglion (SG) neurons. In addition, K-252a did not interfere with nerve growth factor (NGF)- or ciliary neuronotrophic factor (CNTF)-mediated survival of DRG or CG neurons, respectively, but completely blocked the NGF- and CNTF-induced survival of SG neurons. High potassium-induced survival of SG neurons was not affected by K-252a. These results point to differences between various neuronal populations in the signal transduction mechanism for neurotrophic factors.