Taking cell-matrix adhesions to the third dimension

Adhesions between fibroblastic cells and extracellular matrix have been stu died extensively in vitro, but tittle is known about their in vivo counterp arts. Here, we characterized the composition and function of adhesions in t hree-dimensional (3D) matrices derived from tissues or cell culture. "3D-ma trix adhesions" differ from focal and fibrillar adhesions characterized on 2D substrates in their content of alpha (5)beta (1) and alpha (v)beta (3) i ntegrins, paxillin, other cytoskeletal components, and tyrosine phosphoryla tion of focal adhesion kinase (FAK). Relative to 2D substrates, 3D-matrix i nteractions also display enhanced cell biological activities and narrowed i ntegrin usage. These distinctive in vivo 3D-matrix adhesions differ in stru cture, localization, and function from classically described in vitro adhes ions, and as such they may be more biologically relevant to living organism s.