Potent (Ki, 0.6 nM), specific and reversible proteasome inhibitor; no significant inhibitory activity against other enzymes or receptors. Bortezomib inhibits cell proliferation of H460 cells (human non-small cell lung cancer cell lines) with an IC50 of 0.1 µM and has been associated with suppresion of prostate cancer cell lines with an IC90 of 10 nM.