The PathHunter U2OS IL31R/OSMRb Bioassay Kit provides an easy-to-use cell based assay to measure drug potency and detect neutralizing antibodies. This bioassay asseses ligand (e.g. IL-31) based on activation of IL31R/OSMRb Cytokine activity via detection of Dimerization. The included cell line overexpresses ProLink-tagged IL31R/OSMRb and EA-tagged . Activation of IL31R/OSMRb stimulates the recruitment of and produces EFC signal. Bioassay kits are a convenient, ready-to-use format which contains all materials needed to run the assay, including single-use vials of cryopreserved cells, cell plating media, control agonist, detection reagent, and assay plates.