Tumor necrosis factor alpha (TNF-alpha), also called cachectin, is produced by many normal and tumor cells in response to a wide variety of stimuli, including viruses, bacteria, parasites, cytokines and mitogens. In solution, TNF-alpha is a trimeric molecule. Both the transmembrane and the soluble, secreted forms of TNF-alpha are biologically active. TNF-alpha is an extremely pleiotropic cytokine due to the ubiquity of its receptors, to its ability to activate multiple signal transduction pathways and its ability to induce or suppress the expression of a wide number of genes.
Image: TNF-alpha staining of immersion fixed activated mouse T Cells at 15 µg/mL for 3 hours at room temperature (red) and counterstained (green).