PTPN11 and juvenile myelomonocytic leukemia: Drosophila transgenic models that harbor the gain-of-function PTPN11/csw mutations associated with either Noonan syndrome 1 (A72S and N308D) or juvenile myelomonocytic leukemia (E76K) (Oishi et al., 2006) have also been created; each mutation increases RAS/MAPK signaling, with A72S and E76K being the most active.