Calibrator 26 is a lyophilized blend of A2M, Adiponectin, ApoA1, ApoC3, Complement C9, RBP4, and Serpin A1. It is intended for use as an assay calibrator for MSD U-PLEX human 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. A2M, ApoA1 and ApoC3 were purified from human plasma; Adiponectin and Serpin A1 were expressed in a mouse cell line; Complement C9 was purified from human serum; and RBP4 was expressed in a human cell line. Instructions on using Calibrator 26 are provided in U-PLEX Biomarker Group 3 Human Product Inserts.