PSMC3 and neoplasm: We and others have reported that TBP-1 may function as a negative regulator of cell proliferation: inhibition of the oncogenic phenotype of erb-B transformed cells was accompanied by an increase of TBP-1 intracellular levels and, accordingly, its overexpression in erb-B transformed cells strongly inhibited tumour formation in athymic mice [11]; furthermore, TBP-1 overexpression in different cellular contexts diminished cell proliferation [11], [12].