ALDH1A1 and cancer: CSC is also associated with the resistance to radiation and chemotherapy as well as the metastasis of carcinoma,49, 50 thus increased CSC population has been viewed as a poor prognosis indicator of cancer patients.51 ALDH1A1 overexpression has been known to associate with lung cancer malignancy.29 Our study reveals that ALDH1A1 plays an important role in mediating AuO‐induced stemness features and metastatic abilities of lung tumor cells, whereas ALDH1A1 knockdown significantly blocks these effects.