PTPN11 and juvenile myelomonocytic leukemia: Mutations of PTPN11 (the gene codingfor SHP2) cause more than 30% of cases of juvenile myelomonocyticleukemia (JMML) and are variably found in other childhood malignancies.16−19 In addition, SHP2 is required for the survival of receptor tyrosinekinases (RTK)-driven cancer cells,20 playsan important role in resistance to targeted cancer drugs,21 is a mediator of immune checkpoint pathways,22 and is involved in the induction of gastriccarcinoma by Helicobacter pylori.