PTPN11 and central nervous system cancer: Elevated SHP2 phosphorylation status was also evident in four additional human GBM cell lines, U251, U118, A172 and T98G (Supplementary Fig. 4b), and SHP2 inhibition attenuated phosphorylated ERK and AKT levels in two different glioma stem cell (GSC) neurosphere cultures derived from fleshly operated tumour samples from GBM patients (Supplementary Fig. 4c).