Velcade (Bortezomib) inhibits HemSCs proteosome activity and impairs HemSCs viability. Panel A, 20S proteasome chymotrypsin-like peptidase activity assay. HemSCs treated with Velcade, 1nM or 5nM, were lysed and assayed for 20S proteasome activity. Panel B, HemSCs treated with Velcade at the indicated doses were assayed for viability by CellTiter-Glo. Panel C, HemSCs were treated for 24 or 72 hours with Velcade (5nM) or with Dexamethasone (200nM) and then stimulated with or without medium containing full serum and growth factors. Cell lysates were subjected to Western blot analysis with anti-phosphorylated IκB and anti-β-actin.