TNF and breast cancer: In co-cultures of human breast pre-adipocytes and human breast cancer cells, radiation is able to inhibit both proliferation and differentiation of breast fibroblasts through the down-regulation of the two main adipogenic transcription factors CCAAT/enhancer binding protein (C/EBPα) and peroxisome proliferator-activated receptor (PPARγ) and by stimulating the expression of TNFα (Tumor necrosis factor alpha), an anti-adipogenic cytokine secreted by breast malignant epithelial cells.