Polycythemia vera patients with high JAK2V617F mutant allele burden were described to have increased levels of Bcl-2 as well as Bcl-xL, and the Bcl-2/Bcl-W/Bcl-xL inhibitor ABT-737 was shown to preferentially inhibit proliferation and induce mitochondrial depolarization in JAK2V617F mutant erythroblasts as compared to those from healthy subjects [9]. This evidence concerns the gene BCL2L1 and acquired polycythemia vera.