Green tea derived catechins, specifically (-)-epigallocatechin-3-gallate (EGCG) have been shown to have anti-tumor effects through several mechanisms including inhibiting development of the tumor neovasculature. Tumor progression requires development of a vascular network to provide oxygen and nutrients. As the vascular network develops it is contributed to by both co-opting of local blood vessels and infiltration of bone marrow (BM) derived endothelial progenitor cells (EPC). Our long-term goal of developing strategies combining complementary and alternative medicines (CAM) and standard therapies to arrest tumor progression by disrupting the contribution of EPC to the developing tumor neovasculature. We have designed a murine model to accomplish the following specific aims: 1. To determine in a murine transplantable cultured tumor model, whether the inhibition of tumor vasculature formation by catechins is caused by the failure of endothelial cells from adjacent pre-existing vessels to infiltrate the tumor or is a result of blocking bone marrow derived endothelial progenitors trafficking to the tumor. 2. To study the effects of catechins on the developing vasculature in primary and recurrent mammary carcinoma.