The malignant myeloid progenitors in AML secrete TGF-β and thus stimulate the differentiation and proliferation of the common eosinophil-basophil progenitor, thus causing both progressive eosinophilia and basophilia (13, 14), as also shown by Boiocchi et al. (8) (Figure 3). The gene discussed is TGFB1; the disease is acute myeloid leukemia.