The effect of TNF-alpha on cell death in rat fetal brown adipocytes maintained in primary culture was determined, TNF-alpha inhibited proliferation and induced apoptosis in these cells, Most of the cells undergoing apoptosis after TNF-alpha treatment did not express PCNA, suggesting an induction of apoptosis by TNF-alpha in non-proliferative cells, IGF-I but not EGF prevented TNF-alpha-induced apoptosis. (C) 1997 Federation of European Biochemical Societies.