MALT1 (Mucosa-Associated Lymphoid Tissue Lymphoma Translocation Protein 1) is a member of the caspase protease family, containing a caspase-like domain, and is involved in the activation of immune responses and the NF-κB signaling pathway. MALT1 is localized in the cytoplasm and regulates the activation and proliferation of lymphocytes by cleaving specific substrates. It is expressed in various immune cells, especially B cells and T cells. The activity and expression of MALT1 are tightly regulated to maintain immune balance and prevent autoimmune reactions. Gene mutations or overexpression are associated with certain immune diseases and lymphomas, where mutations may lead to abnormal pathway activation, affecting cell survival and differentiation.