BCR and chronic myelogenous leukemia, BCR-ABL1 positive: BCR/ABL is required for the pathogenesis of CML by activating multiple intracellular signal transduction pathways such as Ras/Raf/MAPK, JAK/STAT3, and PI3K/AKT via its protein tyrosine kinase (PTK) interfering with the development of hematopoietic stem cells or progenitor cells.