The results of this experiment show that Hela cells grown in either 1% or 21% O2, as well as cells grown in 1% serum, show reduced levels of GSH after WRN knockdown (Figs 3B and S9A, Supporting Information), demonstrating that WRN depletion influences the cellular antioxidant system and the ability of cancer cells to detoxify ROS. Here, WRN is linked to cancer.