NF1 and plexiform neurofibroma: The absence of functional neurofibromin in NF1 patients leads to uncontrolled Ras signaling and tumor development, prompting phase II clinical trials of various agents, including tipifarnib, pirfenidone, sirolimus, pegylated interferon alfa-2b, and imatinib, with the aim of improving progression-free survival and reducing plexiform neurofibroma volume.