Figure 6. Cancer cell symbiosis and glutamine theory; two theories of cancer metabolism. First theory deposit that cancer cells elaborate survival through glycogenic step which happen by producing lactate via consuming glucose (Warburg effect), and the neighbor cancer cell consumes the secreted lactate to produce ATP through the TCA cycle and oxidative phosphorylation which is known by oxidative step. Glutamine theory includes the conversion of glutamine into glutamate by glutamine synthetase 1, which is further metabolized to α-ketoglutarate by glutamate dehydrogenase and consumed for ATP synthesis through TCA cycle under oxidative condition (54).