We also examined AKT, MET, and STAT3 which we and others have shown to be critical signaling pathways involved in the progression of NF1-related sarcomas.41,42 For the MET receptor we observed an increase in both activated (phosphorylated MET) and total MET in only the Nf1IF MECs (Fig. 4f), yet immunostaining revealed an increase in pMET in both Nf1IF and Nf1PS tumors compared to normal mammary tissue (Supplementary Fig. 5a). This evidence concerns the gene NF1 and sarcoma.