The SVZ areas with fewer abnormal cells, such as the SVZL and its closest tumor segment (TumorL) of Mouse 3 as well as the SVZL of Mouse 6, retained relatively higher levels of Nf1 protein expression than their autologous more advanced tumors (e.g., SVZR and TumorR of Mouse 3; Tumor of Mouse 6) (Fig. 7a, b). Here, NF1 is linked to neoplasm.