For example, ALDH1A2, ALDH2, ALDH3A2 and ALDH9A1 were downregulated in all tumors among the 5 cancer types (Fig. 1a,b,c and Supplemental Fig. 1a), whereas ALDH1B1, ALDH1L2 and ALDH18A1 were most upregulated in tumor parts (Fig. 1d,e,f). This evidence concerns the gene ALDH2 and cancer.