Estrogen affects proliferation and migration of different skin components, thus influencing wound healing processes. The human keratinocyte cell line NCTC 2544 has been used to examine the effects of estrogen, dissect its mechanism of action and characterize receptor subtypes involved. Western blot and immunocytochemical analyses confirmed the expression of estrogen receptors (ERs) alpha and beta, with prevalence in the nuclear and extranuclear compartment, for ER alpha and ER beta respectively. Treatment with 10 nM 17beta-estradiol (17beta-E(2)) and the ER alpha and ER beta selective agonists, 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT; 100 nM), and diarylpropionitrile (DPN; 1 nM) produced a slight but significant increase in cell proliferation, as by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and bromodeoxyuridine incorporation assays, only after a long-term treatment (96 h). Analysis of cell migration by a scratch wound assay showed that 17beta-E(2) (10 nM) accelerated migration between 5 and 24 h after scratching, an effect confirmed by the transwell migration assay. PPT and DPN elicited similar effects. Pre-treatment with the mitogen-activated protein kinase inhibitor, U0126 (1 microM), abolished the ability of 17beta-E(2) and DPN, but not of PPT, to accelerate wound closure. TGF-beta1 (10 ng/ml) produced a similar positive effect on wound closure and the TGF-beta1 receptor antagonist, SB431542 (10 microM), reduced the ability of 17beta-E(2) and PPT to accelerate cell migration, but did not modify DPN effect. It is suggested that estrogen positively affects in vitro wound healing by stimulating cell proliferation after long-term exposure but mainly by accelerating cell migration within a few hours from treatment. Selective activation of ER beta may result in favorable stimulation of wound healing without any increase of transforming growth factor-beta1 production.