Given that lin−CD34+ cells acquire a CD34− differentiated phenotype which is associated with a high level of OLFM4 expression in culture, it is possible that secretion of OLFM4 by differentiated cells generates a milieu supportive for the growth of undifferentiated CML cells in vitro. The gene discussed is OLFM4; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.