SMAD5 and chronic myelogenous leukemia, BCR-ABL1 positive: To investigate the impacts of miR-155 ectopic overexpression on SMAD5 and TGF-βR2 transcripts at the cellular level, the CD34+ CML cells were transfected with miR-155 precursor and analyzed to assess SMAD5 and TGF-βR2 mRNA expression levels.