FIG. 2. FGFR1 and BRAF alterations in pediatric LGG converge on the MAP kinase pathway.
Alterations in FGFR1 result in constitutive activation of the receptor resulting in activation of the MAP kinase pathway. A subset of pediatric LGG also shows mutations in the receptor tyrosine kinase NTRK2. Rare mutations involve other members of this pathway including RAS, NF1 (negative regulator of RAS) and PTPN11, a tyrosine phosphatase adaptor protein. BRAF V600E mutations and the BRAF-KIAA1549 fusion (other rare fusions not illustrated) also result in constitutive kinase activity and aberrant MAP kinase activation. Text in red indicates mutations/alterations.