CD49b is a 150 kD glycoprotein, also known as alpha2 integrin, VLA-2 alpha chain, Integrin alpha2 chain, and HMalpha2. It is a member of the integrin family, expressed on NK cells, a subset of splenic CD4+ T cells, NK-T cells, intestinal intraepithelial and lamina propria lymphocytes, epithelial cells, and platelets. By associating with CD29 (integrin beta1 subunit), CD49b forms the VLA-2 (integrin alpha2beta1 ) complex. It plays a critical role in both adhesion and lymphocyte activation. The primary ligands for CD49b are collagen, laminin, and fibronectin. The HMalpha2 antibody has been shown to be useful for partially blocking CD49b mediated interactions with collagen. Additionally, this antibody blocks staining of splenic NK cells by the monoclonal antibody DX5.