Lastly, antagonistic relationship and cross-talk between BCR-ABL and NOTCH1 activity (which are critical for hematopoietic stem cell self-renewal and survival) in CML progenitor cells were noticed, however, their significance in coexisting CML and CLL remains unclear [21]. The gene discussed is NOTCH1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.