IL3RA and chronic myelogenous leukemia, BCR-ABL1 positive: CD123, also known as the alpha chain of the IL-3 receptor (IL-3Ra), is a membrane protein highly expressed in AML (~90% of cases),197,198 CD123 has also been identified in other myeloid malignancies, such as myelodysplastic syndrome, chronic myelomonocytic leukemia, chronic myeloid leukemia, and myeloproliferative neoplasms,199 CD123 is involved in the JAK, MAPK, and PI3K/AKT signaling pathways, which regulate cell proliferation and differentiation.200