Treatment of these mice with the Il-B08 drug results in decreased levels of phosphorylated SHP2 and phosphorylated ERK and a distinct lack of progression of the low-grade tumours to high-grade gliomas, as evidenced by a reduction in cellularity as determined by a decrease in nuclei and decrease in proliferation of astrocytic cells as determined on haematoxylin and eosin and astrocyte-specific marker glial fibrillary acidic protein (GFAP) (Supplementary Fig. 7). Here, PTPN11 is linked to central nervous system cancer.