FIGURE 6.

A, collagen trypsin sensitivity assay. Acid-extracted collagen was neutralized and incubated with trypsin (1:100 w/w). Aliquots (5 μg) of collagen were removed at indicated time points, and trypsin activity was quenched by adding SDS loading buffer. The amount of proteolysis was assessed by SDS-PAGE staining with Coomassie Blue. B, procollagen processing assay. Primary cultures of smooth muscle cells from Fmod^−/− and wild-type aortas were pulsed with 2.5 μCi/ml of [¹⁴C]proline and chased from 0 to 2 h. Procollagen was acetone-precipitated from the medium, run on SDS-PAGE, and analyzed by autoradiography.