Since it was previously demonstrated that a blockade in the tumor-suppressing TGF-β signals could contribute to miR-155 oncogenic function (Rai et al., 2008[41]), we investigated whether up-regulation of miR-155 enables CD34+ CML cells to escape from the growth-inhibitory effects of TGF-β1 signaling or not. Here, TGFB1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.