The 67D2 monoclonal antibody recognizes human CD164 also known as sialomucin CD164, MUC-24, and multi-glycosylated core protein 24. CD164 is a single pass transmembrane protein with short cytoplasmic tail that is highly N- and O-glycosylated. This protein contains sialic acid and a Ser-Gly motif that may serve as an attachment for a glycosaminoglycan side chain. Three splice variants of CD164 have been reported with apparent molecular weights ranging between 80-100 kD. CD164 is expressed in bone marrow, bone marrow stromal cells, and CD34+ hematopoietic cells myeloid and erythroid progenitors; and activated basophils. Expression has also been reported on a variety of carcinomas and leukemic cells and in the small intestine, colon, lung, and thyroid. CD164 plays a role in cell adhesion and proliferation and acts as a negative signaling molecule for hematopoietic progenitor cells. CD164 has also been reported to be involved in myogenic differentiation and cancer metastasis. The 67D2 antibody has been shown to be useful for the flow cytometric detection of human CD164, Western blotting under non-reducing conditions (detects an 80-100 kD protein as well as a high molecular weight aggregate of approximately 220 kD), and immunofluorescence.