Computational drug repositioning by virtually screening existing drugs for additional therapeutic usage could efficiently accelerate anticancer drug discovery. Herein, a library of 1447Food and Drug Administration(FDA)-approved small molecule drugs was screened insilico for inhibitors of extracellular signal-regulated kinase2(ERK2). Then, invitro kinase assay demonstrated amprenavir, a HIV-1 protease inhibitor, as a potential kinase inhibitor of ERK2. The invivo kinase assay indicated that amprenavir could inhibit ERK2-mediated phosphorylation of BimEL at Ser69. Amprenavir could suppress this phosphorylation in MCF-7 cells, which may further facilitate the association of BimEL with several pro-survival molecules. Additionally, inhibition of ERK2-BimEL signaling pathway by amprenavir could contribute to its anti-proliferative and apoptosis-inducing activity in MCF-7 cells. Finally, invivo tumor growth and immunohistochemical studies confirmed that amprenavir remarkably suppressed tumor proliferation and induce apoptosis in MCF-7 xenografts. Taken together, amprenavir can effectively inhibit the kinase activity of ERK2, and thus induces apoptosis and inhibits tumor growth in human MCF-7 cancer cells both invitro and invivo, making amprenavir a promising candidate for future anticancer therapeutics.