Previously, we demonstrated that an apoptotic peptide from the human immunodeficiency virus-1 (HIV-1) Nef protein, Nef-motif 1 (Nef-M1), was cytotoxic to various cultured human cancer cell lines, and we have characterized Nef- role in activation of apoptosis and inhibition of tumor growth of CRC or BC [2–4]. Here, S100B is linked to breast cancer.