HPRT1 and neoplasm: Silencing the rate limiting enzyme in purine salvage, hypoxanthine guanine phosphoribosyl transferase (HGPRT) when combined with radiation markedly suppressed DMG-H3K27M tumor growth <i>in vivo</i>.<h4>Conclusions</h4>H3K27M expressing cells rely on <i>de novo</i> purine synthesis but adaptively upregulate purine salvage in response to RT.