FC, ICC. IHC, WB
PIN.1 recognizes a ~33-35 kDa protein doublet, corresponding to the apparent molecular mass of the p33 and p35 forms of the cytoplasmic tail of human CD74, a type II transmembrane glycoprotein. It is also known as invariant chain or MHC class II chaperone or MIF (macrophage migration inhibitory factor) receptor. It plays a critical role in the antigen processing leading to antigen presentation by MHC class II to CD4+ T cells. Antigen presenting cells such as B cells, monocytes/macrophages, dendritic cells, and Langerhans cells as well as activated T, carcinomas of lung, renal, gastric and thymic origins express CD74. The CD44 is an integral member of CD74 receptor complex and required for the CD74 signal transduction. CD74’s cytoplasmic domain binds chromatin and regulates transcription and expression of genes involved in immune regulation, cell survival, and hematopoietic cancers. Published report claimed that the urease B subunit released by H. pylori binds to CD74 of gastric epithelial cells leading to induce NF-κB activation and IL-8 production.