Of these, we noticed that aldehyde dehydrogenase family 1 member A1 (ALDH1A1), which has been characterized as a potential cancer stem cell (CSC) marker of lung cancer and its expression is associated with poor outcome and progression of lung cancer.28, 29 Western blot validation showed that AuO induces ALDH1A1 expression in a dose‐dependent manner (Figure 7A). Here, ALDH1A1 is linked to lung cancer.