Proteasome is involved in cell cycle and apoptosis regulation. Its deregulation could participate to oncogenesis.Bortezomib is the first proteasome inhibitor to reach clinical development. Its main adverse events are asthenia, thrombocytopenia and cumulative neurotoxicity which can limits long term use. As single agent, bortezomib displays antitumoral effects in refractory multiple myeloma and mantle cell lymphoma but has only modest activity in solid tumors. Preclinical data suggest that bortezomib could enhance antitumor activity of cytotoxics.Proteasome inhibition is a promising therapeutic pathway, especially in lymphoid malignancies.