SNCG(also designated gamma-synuclein or breast cancer-specific protein 1),with 127-amino acid protein(about 14kDa), belongs to the synuclein family, which also includes alpha- and beta- synuclein.Three synucleins are located in the neuronal cytosol and enriched in presynaptic terminals,while SNCG is also expressed in many other non-neuronal tissues. SNCG is abnormally expressed in a high percentage of tumor tissues of diversified cancer types, including liver, esophagus, colon, gastric, lung, prostate, cervical, and breast cancer, but rarely expressed in tumor-matched nonneoplastic adjacent tissues. High levels of SNCG have been identified in advanced breast carcinomas suggesting a correlation between overexpression of SNCG and breast tumor development.