The HM β1-1 monoclonal antibody specifically binds to the 130-kDa integrin β1 chain (CD29). CD29 is expressed on the cell surface as a heterodimer with one of the distinct integrin-α chains. With α1 through α6 (CD49a through CD49f), it forms the VLA-1 through VLA-6 complexes, respectively, and with αv (CD51), it forms αvβ1 integrin. It also associates with the integrin α7 α8, and α9 chains in non-lymphoid tissues. As a result, CD29 has a broad tissue distribution, including lymphocytes, endothelia, smooth muscle, epithelia, and oocytes. This hamster mAb to a mouse leukocyte antigen has been observed to crossreact with similar populations of rat leukocytes. Source of the immunogen was purified mouse VLA-4 (α4β1, CD49d/CD29).