CD34 and chronic myelogenous leukemia, BCR-ABL1 positive: To determine the effect of SR1-induced hematopoietic cell expansion at the level of CML progenitors and stem cells, we cultured CML-derived CD34+ cells in the presence of 1 μM SR1 or control DMSO for 4, 7 or 14 days and subjected treated cells to clonogenic assays (CFC and LTC-IC) (Fig 4A).