Bortezomib-D8 is the deuterated form of Bortezomib. Bortezomib (T2399) (PS-341) is a reversible and selective proteasome inhibitor that effectively targets threonine residues, inhibiting the 20S proteasome (Ki=0.6 nM). It disrupts the cell cycle, induces apoptosis, and inhibits the nuclear factor NF-κB. Bortezomib (T2399) is noted as the first proteasome inhibitor with anticancer activity.