For example, miR-223 is preferentially expressed in the hematopoietic system with crucial functions in myeloid lineage development, and its expression is repressed in multiple tumors including hepatocellular cancer and acute myeloid leukemia (AML).40–43 Fukao et al.44 found that the expression of miR-223 gene is driven by the myeloid transcription factors PU.1 and C/EBPs. The gene discussed is SPI1; the disease is acute myeloid leukemia.