Brain organotypic slices were obtained from adult male NSG mice as previously described5556. Briefly, 3–8, 300 μm slices per murine brain were obtained with a Leica VT1200 microtome and cultured over 0.4 μm air–liquid interface membranes (Millipore) for 24 h. 200,000 cells were then injected and tumour formation allowed for the next 72 h. Brain slices were then incubated in the presence of the indicated chemicals or the respective DMSO control for 72 h before immunofluorescence analysis. Each condition was done in two technical replicates with a minimum of three biological replicates (n⩾6).
