NQO1 and periodontitis: In the oxidative stress state of periodontitis stimulated by hydrogen peroxide treatment of human periodontal ligament stem cells (PDLSCs), it was found that hydrogen peroxide stimulation increased the content of MDA in PDLSCs, and the mRNA and protein levels of Nrf2 were up-regulated with an increase in its downstream effectors, heme oxygenase-1 (HO-1), NAD(P)H: quinone oxidoreductase 1 (NQO1) and γ-glutamyl cysteine synthetase (γ-GCS) as the exposure concentration increases (41).