Mouse HLA class II histocompatibility antigen gamma chain (CD74), is a single-pass type II membrane glycoprotein which contains 1 thyroglobulin type-1 domain. Mouse CD74 shares 75% and 88% aa sequence identity with human and rat CD74, respectively. CD74 plays an important role in adaptive immunity, inflammation, and cancer. It plays a critical role in MHC class II antigen processing by stabilizing peptide-free class II alpha/beta heterodimers in a complex soon after their synthesis and directing transport of the complex from the endoplasmic reticulum to compartments where peptide loading of class II takes place.CD74 also associates with CD44 and binds with high affinity to the cytokine MIF, leading to inflammatory leukocyte responses, protection from tissue fibrosis, B cell proliferative and survival signaling, and the up-regulation of angiogenic factors in endometrial stromal cells.