The influences of K-252a and staurosporine, protein kinase inhibitors, on neurotrophic effects of basic fibroblast growth factor (bFGF) were investigated in dissociated cell cultures of the striatum, hippocampus and cerebellum of fetal rats. Addition of 1 ng/ml bFGF enhanced the survival of cultured neurons of all brain regions tested. Both K-252a (10-200 nM) and staurosporine (1-100 nM) blocked the survival promoting effects of bFGF in a concentration-dependent manner. These results suggest that bFGF exerts its neurotrophic effects through activation of protein kinase(s).