We have recently reported that OTKs such as FLT3(ITD) and JAK2(V617F) stimulate one-carbon metabolism, resulting in accumulation of the high levels of formaldehyde and that Polθ plays a critical role in protecting AML and MPN cells from the genotoxic effect of formaldehyde [10]. This evidence concerns the gene FLT3 and myeloproliferative neoplasm.