Figure 1.

Type I collagen-embedded HA inhibits EGFR activation. (A) Diagram for experimental 3D culture system. Cells can either be grown on a collagen matrix that has been polymerized with HMW HA (eHA, left), on collagen alone with no exogenously added HA (middle) or in the presence of HMW HA added in soluble form to cell media (sHA, right). (B) Serum starved MDA-MB-231 cells grown in the presence of either collagen-embedded HA (eHA), collagen only or soluble HA (sHA) and were stimulated with EGF (10 ng/ml) for 2 hours (lanes 1–3) or as a control were untreated (lanes 3–6). Collagen gels were prepared as previously described²¹ and 0.125 mg/ml HMW HA was either polymerized into the collagen or added in soluble form to cell media. All HA used was high molecular weight (average 2 mDa). Protein lysates were collected and immunoprecipitated (IP) for EGFR and blotted (IB) for either EGFR (bottom) or phosphotyrosine (pTyr) (top). Molecular weight standards are shown at right.