To test this hypothesis, the present study aimed to determine the following: (a) whether a relative high oral dose of EGCG inhibits tumor growth, tumor angiogenesis, and VEGF expression in an immunocompetent mouse model (C57BL/6) of breast cancer; (b) whether oral EGCG treatment affects angiogenesis and VEGF expression in normal tissues such as the heart and skeletal muscle in the same mice; and (c) whether EGCG inhibits proliferation, migration, VEGF expression, the activation of HIF-1α and NFκB in cultured mouse and human breast cancer cells (E0771, MCF-7 and MDA-MB-231). This evidence concerns the gene NFKB1 and neoplasm.