The size of the cell spreading area of rat aortic smooth muscle cells in two-day-old cultures in a serum-free medium on (A) HDPE; or (B) LDPE in non-treated form (N), treated with plasma for 50, 100 or 300 s, and subsequently grafted with fibronectin (Fn) or bovine serum albumin (BSA). A standard cell culture polystyrene dish (PS) was used as a reference material. Mean ± S.E.M. from 4 to 269 measured cells. ANOVA, Student–Newman–Keuls Method. Statistical significance: ▪ p ≤ 0.05 compared to other experimental groups, indicated by the colors of these groups above the columns.