ALDH1A1 and glioblastoma: In the validation cohorts, lower expressions of ALDH1A1, ALDH6A1, ALDH2, ALDH5A1 were observed in GBM compared to LGG, while ALDH16A1, ALDH3B1 and ALDH3A1 were preferentially enriched in GBM (Figures 1B–D).