In order to test if cell-surface FAS expression was also modulated by DAC under in vivo relevant oxygen fractions, we investigated FAS expression by GDCs and GIC at 1% O2 (i.e. hypoxia, condition of oxygen deprivation likely to occur at the brain tumour site) and at 5% O2 (i.e. physioxia, found for example in well oxygenated zones of tumour). The gene discussed is FAS; the disease is neoplasm.