A normally functioning breast cell has estrogen receptors, into which the body''s natural estrogens fit like a key into a lock, regulating cell growth. Doctors can exploit these receptors by using drugs that attach to them, delivering chemotherapy to cancerous cells with drugs like tamoxifen. Genistein, a component of soy foods might suppress the development of breast cancer. A research team at the University of Arizona Cancer Center revealed how genistein can protect BRCA1, a gene that plays a pivotal role in thwarting tumor development in breast tissue.