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 Western 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 Western blot.Results:MDA-MB-231 cells expressed a relatively higher level of neuregulin.In Western 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. Objective: To explore the effects of neuregulin on ErbB2 receptor signaling 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 Western 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 Results: MDA-MB-231 cells expressed a relatively higher level of neuregulin. In Western 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 of MMP (P <0.05) .Conclusion: Our study indicates that neuregulins are synthesized in MDA-MB-231 cells as (-2) and MMP-9 were lower 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.