Merriam-Webster Collegiate Dictionary - tumor necrosis factor

 noun  Date: 1975 a protein that is produced chiefly by monocytes and macrophages in response especially to endotoxins and that mediates inflammation and induces the destruction of some tumor cells and the activation of white blood cells TUMOR SUPPRESSOR GENE  noun  Date: 1985 any of a class of genes (as p53) that act in normal cells to inhibit unrestrained cell division and that when inactivated (as by mutation) place the cell at increased risk for malignant proliferation