IDH1 and leukemia: However, although the expression of mutant IDH1/2 both in vitro and in vivo leads to the accumulation of undifferentiated hematopoietic cells [37,39,59,61], it is not sufficient to drive leukemia development and in fact needs the co-presence of high levels of 2-HG, which bias these cells toward the myeloid lineage [62].