The constitutive activation of STAT5 by BCR-ABL then leads to the upregulation of genes associated with CML such as Bcl-x, Mcl-1, and D 1⁄2, and this hyperactivation leads to the dysregulated proliferation of cells (136, 138). The gene discussed is STAT5B; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.