The failure of the protein degradation machinery namely «the ubiquitin -proteasome pathway " is involved in the onset of various diseases. In particular with different forms of cancer, related to the degradation of proteins such as transcription factors, regulators cell cycle proteins or tumor suppressors. Mainly localized in the nucleus and cytoplasm of cells, the proteasome can be detected in the cell culture supernatant or in the peripheral blood (plasma or serum) of patients. The aim of this work is to confirm a significant presence of circulating proteasome (1264