rate of glycolysis decreases further which enhances the apoptosis rate. autophagy autophagy is when a cell digests some of its own organelles by lysosomal degradation. autophagy is employed to remove damaged organelles, or under starvation conditions to provide additional nutrients. normally, autophagy occurs by the tsc-mtor pathway, but can be induced by ros. tigar, even at very low levels, inhibits autophagy by decreasing ros levels. the mechanism by which tigar does this is independent from the mtor pathway, but the exact details are unknown. possible roles in cancer tigar can promote development or inhibition of several cancers depending on the cellular context. tigar can have some effect on three characteristics of cancer; the ability to evade apoptosis, uncontrolled cell division, and altered metabolism. many cancer cells have altered metabolism where the rate of glycolysis and anaerobic respiration are very high whilst oxidative respiration is low, which is called the warburg effect (or aerobic glycolysis). this allows cancer cells to survive under low oxygen conditions, and use molecules from respiratory pathways to synthesise amino acids and nucleic acids to maintain rapid growth. in glioma, a type of brain cancer, tigar can be over-expressed where it has oncogenic-like effects. in this case, tigar acts to maintain energy levels for increased growth by increasing respiration (conferring altered metabolism), and also protects glioma cells against hypoxia-induced apoptosis by decreasing ros (conferring evasion of apoptosis). tigar is also overexpressed in some breast cancers. in multiple myeloma, tigar expression is linked to the activity of muc-1. muc-1 is an oncoprotein that is overexpressed in multiple myeloma and protects these cells from ros-induced apoptosis by maintaining tigar activity. when muc-1 activity is removed, levels of tigar decline and cells undergo ros-induced apoptosis. in a type of head and neck cancer known as nasopharyngeal cancer, the onco-protein kinase c-met maintains tigar expression. tigar increases glycolytic rate and nadph levels which allows the cancer cells to maintain fast growth rates. however, tigar may also have an inhibitory effect on cancer development by preventing cellular proliferation through its role in p53 -mediated cell cycle arrest.