Luciferase assay showed that CuET treatment had no effect on transcriptional activity of GV238-ALDH1A3 in CRC cells compared with the control (Supplementary Fig. S4a), suggesting that inhibition of ALDH1A3 induced by CuET does not occur at the transcriptional level. The gene discussed is ALDH1A3; the disease is colorectal carcinoma.