NOX4 and cancer: In this work, we observed that TGFβ upregulated NOX4 expression in patient‐derived GSC (Figs 1 and 2), a regulatory event that takes place in other non‐tumoural and in cancer cell types such as hepatocellular carcinoma [42, 43], with the immediate consequence of increasing the intracellular ROS levels (Fig. 2).