Table 3. Proteasome inhibition in B-cell lymphoma subtypes expressing differing levels of immunoproteasome by β5i- and β5c-selective compounds 5 and 14 respectively compared with bortezomib.

Inhibition of the β5 sites of the constitutive and immunoproteasome was assessed in the indicated B-cell lymphoma lines (20000 cells per well) in situ using the Proteasome-Glo™ assay. Cells were incubated with compound for 1 h and assays were performed with the chymotrypsin-like substrate Suc-LLVY-aminoluciferin as described in the Experimental section. The results are the means±S.E.M. for triplicate determinations.

	Proteasome-Glo™ β5 IC50 (nM)
Compound	OCI-Ly10	WSU-DLCL2	Karpas-1106P
5	1300±400	320±120	310±150
14	39±7.6	190±76	850±240
Bortezomib	2.9±0.25	2.7±0.26	3.3±0.40