CD29 (integrin β-1 / gpIIa) is a cell adhesion molecule appearing on platelets, as the common β subunit of the very late activation antigen (VLA), and as a component of various protein complexes binding to extracellular matrix proteins. The CD29 is expressed at the cell surface exclusively as part of a heterodimer, in association with one of at least nine different integrin α subunits (α1 , α2 , α3, α4 , α5 , α6, α7, α8 , and αv). With the exception of red blood cells and possible weak expression on granulocytes, CD29 is expressed on nearly all cell and tissue types.