Fetal bovine serum (FBS) restriction and bovine serum albumin (BSA) supplementation affect the expression of key myogenic proteins by cultured e19 fetal rat lung lipofibroblasts (LIFs). In e19 LIFs, FBS restriction increased the expression of fibronectin, calponin, β-catenin, and LEF-1 (A); BSA supplementation blocked these effects (B-E). After a 24-hour incubation period, FBS-restricted cells demonstrated increased β-catenin levels along with its increased nuclear translocation, increased LEF-1 levels, and decreased lipid content; all of these effects were blocked by BSA supplementation (F). * = P < .05 versus 10% FBS and # = P < .05 versus 0% FBS; N = 4. e19 indicates embryonic day 19; LEF-1, lymphoid enhancer-binding factor 1.