They are considered to be the most frequent mechanism of mitogen-activated protein kinase activation, alternative to KIAA1549-BRAF fusion and BRAF mutations.    ///    "They are considered to be the most frequent mechanism of mitogen-activated protein kinase activation, alternative to KIAA1549-BRAF fusion and BRAF mutations. "    ///    "Despite their histologic similarity with pilocytic astrocytomas (PAs), RGNTs do not harbor KIAA1549-BRAF fusions or BRAF mutations, which represent the most common genetic alteration in PAs. "