LRIG1 and glioblastoma: We have previously shown that the soluble fragment of LRIG1 (sLRIG1, Figure 1A) inhibits GBM proliferation in vivo and in vitro in different GBM cells and patient-derived orthotopic xenografts (PDOX), irrespective of their EGFR status.22 We established a GBM cell line expressing sLRIG1 (Supplementary Figure S1A) that presented a significant proliferation defect (Figure 1B), which was associated with a dramatic reduction in EGFRvIII protein levels (Figure 1C).