The association between TGF-β1 and SMAD 1/5 has been detected in epithelial and endothelial cells (Daly et al., 2008[14]; Liu et al., 2009[26]), thus, as the first step, we sought to investigate a possible mechanism for SMAD5 activation in CML cells. This evidence concerns the gene SMAD5 and chronic myelogenous leukemia, BCR-ABL1 positive.