TNFAIP3 and neoplasm: Previous studies have identified A20 as a tumour suppressor protein in B cells where its inactivation leads to constitutive or aberrant NF-κB activation mediating increased cell proliferation and survival of subsets of B-lineage lymphomas.41, 42, 43 Also in the intestine, A20 acts as a tumor suppressor for colon carcinogenesis.32, 44 In other cell types, however, A20 has been ascribed pro-tumorigenic activities, likely connected to its anti-apoptotic functions.12 These observations suggest that depending on the cell type and tumor stage, A20 may act as a tumor suppressor or a tumor enhancer.