CSF2 and acute myeloid leukemia: We confirmed the strong activation of the GM-CSF pathway in AML cells, as assessed by an improved phosphorylation of the downstream Stat3 transcription factor (Figure 3E) and enhanced transcription of the Stat3 specific target genes, c-Myc, c-Fos and Ccnd1 (Figure 3F), known to be involved in cell cycling and proliferation of leukemic cells [8].