Functional analysis of FGF-2 released from the matrix by TSP-1. Subendothelial matrix was preincubated with biotin-labeled FGF-2 (▪) or not preincubated (□; control), and then treated with TSP-1 or plain buffer (spontaneously released FGF-2). Released material was then analyzed by Western blot (C) and, in parallel, plated on endothelial cells to measure FGF-2 binding to cell surface (A) and ability to induce cell proliferation (B), as described in “Materials and methods.” (A) Samples were added to BAECs and incubated for 2 hours at 4°C. After washes, cells were lysed and the amount of bound FGF-2 was analyzed by dot-blot analysis. Data (mean ± SD of triplicates) are expressed as arbitrary units of optical density (IOD). (B) Samples were added to BAECs and the number of proliferated cells was evaluated 72 h later. Anti-TGFβ antibodies did not revert the lack of proliferative activity of FGF-2 released from the ECM by TSP-1 (▨). Data (mean ± SD of triplicates) are expressed as absorbance.