“…Antibodies against the integrin receptor subunits alpha 2 beta 1 inhibit cell contraction of collagen gels, indicating that the contractile forces are transmitted to collagen matrices through integrin receptors (Gullberg et al, 1990;Klein et al, 1991;Schiro et al, 1991). A number of studies have confirmed that fibroblast contraction of collagen is stimulated by exogenous factors, the most common source being serum (Bell et al, 1979; 0 1993 WILEY-LISS, INC Steinberg et al, 1980;Guidry and Grinnell, 1985;Guidry et al, 1990). The contraction-stimulating activity in serum can be attributed, at least in part, to the well-established effects of transforming growth factor beta (TGFP) (Montesano and Orci, 1988;Fukamizo and Grinnell, 1990;Raymond and Thompson, 1990) and platelet-derived growth factor (PDGF) (Anderson et al, 1990;Clark et al, 1989;Gullberg et al, 1990), which are released from platelets during blood coagulation.…”