G6PD and bone osteosarcoma: Furthermore, in HeLa cells, ATM localises in the nucleus in response to endogenous mitochondrial oxidative stress, independently of DNA damage response, whilst promoting glucose flux through the pentose phosphate pathway (PPP) and increasing cellular anti-oxidant capacity by increasing glucose-6-phosphate dehydrogenase (G6PD) in bone osteosarcoma cells (U2OS)11.