The effect of alpha-tocopherol (vitamin E) on gene expression in rat vascular smooth muscle cells was studied by the differential display technique. One gene out of about 1000 genes analyzed, identified as alpha-tropomyosin, showed an increased transcription level caused by alpha-tocopherol treatment. Northern and Western blot analysis revealed a time-dependent transient up-regulation of the amount of mRNA (peak between 2 and 3 h) and protein (peak at 5 h) in alpha-tocopherol-treated cells. No effect was observed in cells treated with beta-tocopherol.