UAS regulatory sequences drive expression of a chimeric protein in which the unc-5 cytoplasmic domain has been replaced by the cytoplasmic domain of robo1 (unc-5 amino acids 32-536 are fused via a Ser-Phe linker to robo1 amino acids 940-1395). The coding sequence is tagged at the N-terminal end with the Tag:SS(wg) signal sequence followed by three copies of Tag:HA.