TNF was named prior to the major work done on apoptosis- The terms refers to the fact that TNF caused necrosis of the tumor, in the days when necrosis just meant death. That being said, TNFa has a very large number of functions, including activation of the immune system. In addition, TNFa is actually a survival factor for many neuronal cells. In death pathways, TNF can stimulate classic caspase-mediated apoptosis, mitochondrial-mediated non-caspace programmed cell death, and necrosis, depending on the cell, the presence of other mediating signal molecules, and the energy state of the cell. The old rule"one protein, one function" is a hopelessly obsolete concept.