The invention relates to an antagonist of one or more of Rho family members having ability to elicit neurite outgrowth from cultured neurons in an assay method which includes culturing neurons on a substrate that incorporates a growth-inhibiting amount of Rho family member and exposing the cultured neurons to a candidate Rho family member antagonist agent to permit neuron growth. Candidates which elicit neurite outgrowth from the cultured neurons are thus identified as Rho family antagonists.