SMAD5 and chronic myelogenous leukemia, BCR-ABL1 positive: These results indicated that CD34+ CML cells with high expression of miR-155 represent decreased expression levels of SMAD5 and TGF-βR2 mRNAs; therefore, we proposed that overexpression of miR-155 might be negatively correlated with low levels of SMAD5 and TGF-βR2.