Since it has been suggested that TGF-β signaling is essential for regulating the survival of CML stem cells (Naka and Hirao, 2017[32]), we sought to measure the expression levels of two key members of the TGF-β pathway (SMAD5 and TGF-βR2) in CD34+ CML and normal cells. Here, CD34 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.