CD34 and chronic myelogenous leukemia, BCR-ABL1 positive: Furthermore, we have not considered a protective effect of G-CSF on leukemic stem cells [50] since cytokines seem to protect only bulk CD34+ cells from tyrosine kinase inhibition and about 10% of primitive CML stem cells survive a 12 day exposure to dasatinib in the absence of any added cytokines [51].