M1i-124 selectively inhibits NF-κB signaling, cytokine production, and proliferation of MALT1-dependent ABC-DLBCL cells without affecting MALT1-independent GCB-DLBCL cells, promotes selective ABC-DLBCL cell death, and inhibits ABC-DLBCL tumor growth in xenograft models. The gene discussed is NFKB1; the disease is aneurysmal bone cyst.