NSC697923 is a cell permeable, potent and selective inhibitor of the Ub-conjugating enzyme (E2) complex Ubc13-Uev1A. It selectively inhibits PMA-induced NF-κB activation, and also inhibits IκBα phosphorylation by both RANKL and LPS. It impedes the formation of the Ubc13 and ubiquitin thioester conjugate and suppresses constitutive NF-κB activity in ABC-DLBCL cells. It inhibits the proliferation and survival of ABC-DLBCL cells and GCB-DLBCL cells, suggesting the Ubc13-Uev1A may be crucial for DLBCL growth. In neuroblastoma (NB) cell lines, NSC697923 shows cytotoxic effect, and inhibits both anchorage-dependent and -independent colony formation. It also shows in vivo antitumor efficacy in NB orthotopic xenografts.