Information VR23 VR23 is a potent proteasome inhibitor with IC50 of 1 nM, 50-100 nM, and 3 μM for trypsin-like proteasomes, chymotrypsin-like proteasomes, and caspase-like proteasomes, respectively. Targets Trypsin-like proteasomes (in Hela cells); Chymotrypsin-like proteasomes (in Hela cells); Caspase-like proteasomes (in Hela cells) 1 nM; 100 nM; 3 μM In vitro In HeLa cells, VR23 induces ubiquitinated proteins accumulation. In RPMI 8226 and KAS 6 cells, VR23 inhibits cell growth with IC50 of 2.94 and 1.46 μM, respectively. VR23 is also equally effective on both bortezomib (BTZ)-sensitive and -resistant RPMI 8226 and ANBL6 cells cells. When used in combination of bortezomib in the cells above, VR23 shows synergistic effects on cell growth inhibition. In addition, VR23 selectively induces cancer cell apoptosis by causing the accumulation of ubiquitinated cyclin E. In vivo In ATH490 athymic mice engrafted with MDA-MB-231 metastatic breast cancer cells, VR23 (30mg/kg, i.p.) shows effective antitumor and antiangiogenic activities. VR23 also reduces adverse effects caused by paclitaxel in mice. Cell Research(from reference) Cell lines：RPMI 8226, KAS 6, 184B5, and MCF10A cells; bortezomib-resistant RPMI 8226 cells and bortezomib-resistant ANBL6 cells Concentrations：~20 μM