Monoallelic loss of BECN1 has been observed in about 40% of human breast cancers (Aita et al., 1999, Li et al., 2010), and enforced expression of BECN1 in breast cancer cells with allelic loss of 17q21 inhibits proliferation and tumorigenesis (Liang et al., 1999). The gene discussed is BECN1; the disease is breast cancer.