Proliferation of hepatic stellate cells (HSCs) is central for the development of fibrosis during liver injury. We have shown previously that butein (3,4,2',4'-tetrahydroxychalcone) suppresses myofibroblastic differentiation of rat HSCs. Our aim in this study was to determine whether a new synthetic chalcone derivative, 2',4',6'-tris(methoxymethoxy) chalcone (TMMC) inhibits HSC proliferation induced by serum- or platelet-derived growth factor (PDGF). TMMC significantly inhibited growth factor-induced HSC proliferation. The inhibition of PDGF-induced proliferation by TMMC was associated with the phosphatidylinositol 3-kinase-Akt-p70(S6K) pathways. TMMC induced the expression of heme oxygenase 1 (HO-1) in HSCs. Using the chemical inhibitor tin protoporphyrin, we also found that the inhibitory action of TMMC on PDGF-induced proliferation is mediated by HO-1. Glutathione (GSH) depletion produced by TMMC activated extracellular signal-regulated kinase (ERK), which led to c-Fos expression and transactivation of activator protein 1 (AP-1) and HO-1 gene expression in the HSCs. These results demonstrate that TMMC preferentially activates ERK and that this activation leads to the transcriptional activation of AP-1 and consequently to HO-1 expression. HO-1 expression might be responsible for the antiproliferative effect of TMMC on HSCs.