A20 (also called TNFAIP3), a ubiquitin-modifying enzyme acting as negative regulator of NF-κB, is inactivated through epigenetic silencing, deletion and/or somatic mutations in a significant portion of the ABC subtype of diffuse large B-cell lymphoma (DLBCL) [10], of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) [11–13] and of Hodgkin’s lymphoma [12,14]. Here, NFKB1 is linked to MALT lymphoma.