NF1 and neoplasm: We specifically chose the brainstem for several reasons: (1) it is the second most common brain location for pediatric LGGs arising in children with NF1 [21, 42], (2) we have previously used brainstem injections for murine Nf1-OPG stem cell tumor modeling [47], and (3) injections into the mouse optic nerve, the most common site for NF1-pediatric LGGs, create major tissue damage and induce a reactive immune microenvironment.