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Objective: To explore the effects of neuregulins on ErbB2 receptor signal transduction pathway activation, and invasion and metastasis of non-overexpression ErbB2 breast cancer cell MDA-MB-231. Methods: The expressions of neuregulin were detected by immunocytochemistry and West blot. MDA-MB-231 cells were treated with ErbB2 kinase inhibitor AG825. Proliferations were measured with MTT assay. Invasion and metastasis of MDA-ME-231 cells were evaluated with transwell chamber. The enzyme activities of MMP-2 and MMP-9 were detected by gelatin zymography. The expressions of MMP-2 and HIF-1α were detected by West blot.Results: MDA-MB-231 cells expressed a relatively higher level of neuregulin. In West blot, the positive reaction band was found at 44KD which coincides with the molecular weight of NRG. When MDA-MB-231 cells were treated with AG825, the proliferation was inhibited in a time-dose-dependent manner (P＜0.01), invasion and metastasis were also depressed (P＜0.05). The enzyme activities of MMP-2 and MMP-9 were lower (P＜0.05). The expression levels of MMP-2 and HIF-1α were decreased (P＜0.05).Conclusion: Our study indicates that neuregulins are synthesized in MDA-MB-231 cells as transmembrane proteins, neuregulins could activate ErbB2 receptor signal transduction pathway by autocrine or paracrine secretion, and induce invasion and metastasis of MDA-MB-231 cells.