Previous KINOMEscan data showed that a pyrazolopyrimidine inhibitor very similar in structure to WZ4-49-1 does not bind to Hck, Lyn or Syk [16], strongly suggesting that its growth suppressive activities in Flt3-ITD+ AML cell lines are primarily due to inhibition of Fes and not these other AML-associated kinases. The gene discussed is HCK; the disease is acute myeloid leukemia.