Furthermore, TG2 knockdown or its pharmacological inhibition by monodansylcadaverine (MDC), a TG2 amine substrate competitive inhibitor, attenuated the expression of ID1 and suppressed tumorigenicity in a glioblastoma (GBM) orthotopic mouse model by blocking the CD44-high GSCs, thus suggesting that inhibition of TG2 transamidating activity might be an effective strategy to block CD44-high GBMs [55]. This evidence concerns the gene ID1 and glioblastoma.