UASt regulatory sequences drive expression of the spCFP1-10 split fluorescent protein fragment fused to a membrane targeting sequence (Tag:M(hCD4)). Designed to be used in a CRASP (CFP reconstitution across synaptic partners) assay, in which complementary split fluorescent protein fragments expressed on the extracellular membrane of different neurons can reconstitute a functional fluorescent protein at points of contact between the neurons.