SLC1A3 and neoplasm: In conclusion, we have established and validated a novel approach to recombine a regionally defined cell population using direct application of the tamoxifen metabolite endoxifen in the CNS and we demonstrate its usefulness for specific biological questions, in that endoxifen-induced GLAST::CreERT2 mediated recombination of tumour suppressor genes results in the formation of brain tumours.