MALT1 is a paracaspase, which is related to the caspase (cysteine-aspartic proteases) family of proteases but cleaves after Arg residues instead of Asp. MALT1 cleavage activity is linked to the pathogenesis of activated B cell-like diffuse large B cell lymphoma (ABC-DLBCL), a chemoresistant form of DLBCL. MALT1 is a unique paracaspase protein that transduces aberrant oncogenic signaling in ABC-DLBCL. MALT1 represents a potentially important therapeutic target for ABC-DLBCL and MALT lymphoma. MALT1 small molecule inhibitors might be useful chemical tools for studying MALT1 biology and treating MALT1-addicted tumors.