 In 2013, two conditional knockout mouse models, called "Dhh-Cre;Nf1flox/flox" (which develops neurofibromas similar to those found in NF1 patients) and "Mx1-Cre;Nf1flox/flox" (which develops myeloproliferative neoplasms similar to those found in NF1 juvenile myelomonocytic leukemia/JMML) were used to study the effects of the specific MEK inhibitor PD032590 on tumor progression.The inhibitor demonstrated a remarkable response in tumor regression and in hematologic improvement.Based on these results, phase I and later phase II clinical trials were then conducted in children with inoperable NF1-related plexiform neurofibromas, using Selumetinib, an oral selective MEK inhibitor used previously in several advanced adult neoplasms.