A heterozygous mutation in one of them, on the other hand, will make the cell produce the oncometabolite, (D)-2HG and at the same time allow this particular (D)-2HG-producing tumor cell to produce enough citrate (i.e. through the other wild type isoform (e.g. wild type IDH2 in a tumor cell harboring neomorphic f IDH1) and utilize it to survive and divide. This evidence concerns the gene IDH1 and neoplasm.