a, NLGN3 western blot illustrating NLGN3 secreted into conditioned medium from optogenetically stimulated Thy1::ChR2; NSG cortical slices (ChR2 stim slice) or SU-DIPG-XIII xenograft-bearing Thy1::ChR2; NSG cortical slices (ChR2 stim slice with xenograft). Performed in biological duplicate. b, NLGN3 western blot illustrating NLGN3 secreted into conditioned medium from wild-type brain slices, wild-type brain slices bearing xenografts of adult GBM SU-GBM035 (WT + xeno), or from Nlgn3 knockout brains bearing SU-GBM035 xenografts (Nlgn3 KO + xeno) in the absence (left three lanes) or presence (right three lanes) of 200 nM ADAM10 inhibitor GI254023X (+ADAM10i). Performed in biological triplicate. c, NLGN3 western blot illustrating glioma cell secretion of NLGN3 in vitro at baseline medium conditions (aCSF), following exposure to recombinant NLGN3 with subsequent washing (NLGN3), at baseline medium conditions in the presence of ADAM10 inhibitor GI254023X (aCSF + ADAM10i) or after NLGN3 exposure in the presence of ADAM10 inhibitor (NLGN3 + ADAM10i). Performed in biological triplicate. d, mRNA expression levels of ADAM10 in primary tumour and cultures of DIPG by RNA-seq with values reported as FPKM12,42 (left; n = 8 primary samples, n = 7 culture samples) and in 493 individual adult glioblastoma samples from TCGA43 (right). Values are reported as robust multi-array averages (RMA; right). Boxes show the median, 25th and 75th percentiles, error bars show the minima and maxima.