IDH1 and cancer: Because a remarkable depletion of the accumulated glutamate in R132H/+ cells occurred in response to cytostatic concentrations of metformin, it is reasonable to suggest that the metformin-hypersensitive phenotype of IDH1 mutated cells is related to the ability of metformin to negatively impact the enhanced engagement of IDH1-mutated cancer cells to TCA anaplerosis of glutamine.