Calibrator 12 is a lyophilized blend of 8 recombinant mouse proteins: IL-9, IL-17A/F, IP-10, MCP-1, MIP-1α, MIP-1β, MIP-2, and MIP-3α. It is intended for use as an assay calibrator for MSD U-PLEX mouse assays that measure any of the included proteins. The utility of this product has not been evaluated in other applications. Individual analyte concentrations are provided in the lot-specific certificates of analysis. IL-17A/F, IP-10, MCP-1, MIP-1α, MIP-1β, MIP-2, and MIP-3α were expressed in E.coli. IL-9 was expressed in insect cells. Instructions on using Calibrator 12 are provided in U-PLEX Group 1 Mouse Product Inserts.