TNF and breast cancer: On the contrary, in rat models of chemically induced breast cancer and an intravenously triggered metastatic form of the disease following breast cancer cell infusion directly to the circulation system, animals with β-endorphin-releasing neurons transplanted into the hypothalamus had reduced levels of tumour necrosis factor α (Tnf-α) and Nf-κB, as well as Snail, Slug, and Twist, with a concomitant decline in N-cadherin and increased level of E-cadherin in tumours excised from mammary glands, as compared to animals with control transplants (Table 2).