Provided below are ELISA kits targeting marginal zone B and B1 cell specific protein, a human protein encoded by MZB1. This protein is 189 amino acids long, with a mass of 20.7 kDa, and is a member of the MZB1 family. 5 isoforms have been identified. This is reported to be a cytoplasmic, nuclear and secreted protein. Other alias names for this protein include: HSPC190, caspase-2 binding protein, mesenteric estrogen-dependent adipose 7, plasma cell-induced ER protein 1, and plasma cell-induced resident ER protein.