JAK2 and hematologic disorder: We found previously that inhibition of the aberrant tyrosine kinases involved in pathogenesis of various hematological malignancies, such as BCR/ABL, Jak2-V617F, and Flt3-ITD, also down regulated the Chk1 activation to induce apoptosis synergistically with chemotherapeutics in cells expressing these aberrant kinases [17].