Lymphotoxin alpha, a member of the tumor necrosis factor family, is a cytokine produced by lymphocytes. LT-α1-β2 can interact with receptors such as LT-β receptors. Absence of LT-β on cell surfaces will diminish the ability of LT-α to form LT-α1-β2, thus decreasing its effective ability as a cytokine. LT-α mediates a large variety of inflammatory, immunostimulatory, and antiviral responses. LT-α is also involved in the formation of secondary lymphoid organs during development and plays a role in apoptosis. In LT-α knockout mice, Peyer's patches and lymph nodes will fail to develop, thus illustrating the cytokine's essential role in immunological development. As a cytotoxic protein, LT-α causes the destruction of cancerous cell lines, activates signaling pathways, and effectively kills transformed tumor cells. However, mice with overexpression of LT-α or LT-β showed increased tumor growth and metastasis in several models of cancer. In other studies, mice with gene knockout of LT-α showed enhanced tumor growth, implicating possible protective role of LT-α in cancer. However, these studies utilized mice with complete LT-α deficiency that did not allow to distinguish effects of soluble versus membrane-associated LT.