SHMT2 and chronic myelogenous leukemia, BCR-ABL1 positive: Interestingly, while genetic ablation of SHMT2 did not change the ability of HCT116 cells to synthesise ATP, it dramatically decreased the incorporation of serine into ATP in all three CML cell lines, indicating that mitochondrial folate metabolism is indispensable for purine synthesis in CML cells (Fig. 1i and Supplementary Fig. 2p).