SMAD4 and chronic myelogenous leukemia, BCR-ABL1 positive: We examined the serum levels of ligand TGFβ1 and expression of its receptors TGFβR1 and TGFβR2, Co-Smad (SMAD4) and I-Smad (SMAD7) in CML patients, Association between genetic mutations in study genes and CML was also analyzed in a subset of CML patients.