Signal transduction pathways involved in acute myeloid leukemia (AML).

The cartoon on the left shows the signaling transduction pathway from the RTK through ras. Binding of ligand (L) to the RTK causes phosphorylation of Grb-2, which forms a complex with the nucleotide exchange protein SOS. The interaction of Grb-2/SOS with the farnesylated (F) ras protein causes ras-GDP to become activated to ras-GTP. This in turn phosphorylates and activates Rac, Raf, and the PI3K pathways leading to changes in cytoskeletal organization, proliferation, and anti-apoptotic pathways. The activated ras-GTP is inactivated by GAP and NF-1. The cartoon on the right shows the Jak/STAT pathway. Ligand binding causes phosphorylation of Jaks; these in turn may activate the ras pathway (dotted arrow), and phosphorylate Stats. These Stats form either homodimers with like Stats (green ovals) or form heterodimer complexes with other members of the Stat family (purple ovals). These dimers translocate to the nucleus where they activate the transcription of specific gene targets.