These data demonstrate that the induction of tTG expression by ALDH1A3 in MES GSCs is maintained in other cell types expressing ALDH1 isozymes, thus raising the intriguing possibility that tTG may provide a sensitive marker and therapeutic target for MES GSCs and HGG, as well as in other cancer cells expressing ALDH1 family enzymes. This evidence concerns the gene ALDH1A1 and cancer.