In vitro activity: NSC697923 selectively inhibits PMA-induced NF-κB activation, and also inhibits IκBα phosphorylation by both RANKL and LPS. NSC697923 impedes the formation of the Ubc13 and ubiquitin thioester conjugate and suppresses constitutive NF-κB activity in ABC-DLBCL cells. In addition, NSC697923 inhibits the proliferation and survival of ABC-DLBCL cells and GCB-DLBCL cells, and also induces apoptosis of primary DLBCL cells. In neuroblastoma (NB) cell lines, NSC697923 shows cytotoxic effect, and inhibits both anchorage-dependent and -independent colony formation

Kinase Assay: The reactions are carried out at 37°C for 40 minutes in a buffer containing 50mM Tris-HCl, pH 7.5, 5mM MgCl2, 200μM ATP, 120μM Ub (U-100H), and 0.1μM E1 (E-304). For Ubc13-mediated Ub chain synthesis, the reaction mixture includes 0.2 μM Ubc13 (E2-600) and 0.2 mM Uev1A (E2-662) with or without GST-TRAF6. For UbcH5c-catalyzed ubiquitination, UbcH5c (E2-627) instead of Ubc13 and Uev1A is used in the reaction. Compound NSC697923 is added into the reaction mixtures at the indicated concentrations. The reactions are terminated with an equal volume of SDS-PAGE sample buffer and the products are analyzed by Western blotting with a Ub-specific antibody. For detecting the E2-Ub (Ubc13~Ub or UbcH5c~Ub) thioester conjugates, the reactions are carried out as described in “In vitro ubiquitination assay” without GST-TRAF6. The reactions are terminated by the addition of the SDS-PAGE sample buffer without a reducing agent unless specified. The products are analyzed by Western blotting with an anti-Ubc13 or anti-UbcH5c antibody.

Cell Assay: Cell viability is measured by trypan blue exclusion assay.

Blood. 2012 Aug 23;120(8):1668-77; Cell Death Dis. 2014 Feb 20;5:e1079.