Effect serum and bFGF on TFPI mRNA accumulation in PASMC. Quiescent PASMC were treated with basal medium alone or the basal medium containing serum (10% vol/vol) or bFGF/heparin (10 ng/15 U/mL) for 8, 24, and 48 hours. Total RNA was isolated from the cells, 10 μg of each RNA sample was used for Northern blot analysis, and the blot was hybridized with a radiolabeled TFPI cDNA probe and exposed to x-ray film (A). Because the TFPI 1.4-kb message in these cells was about 20% of the total TFPI message and migrated as a diffused band, it was not visible clearly in the figure. Ethidium bromide staining of 28S and 18S ribosomal RNA of the same samples indicates equal RNA loading. (B) Quantitative analysis of hybridization signal obtained with PhosphorImager (n = 3). The symbols are as follows: C, control treated (basal medium alone); S, serum treated; F, bFGF treated.