HDAC inhibitors can suppress the expression of MMP14 in GBM, and the inhibition of MMP14 helps to reduce tumor angiogenesis, inflammation, cancer cell invasion, and metastasis, thereby promoting tumor radiotherapy resistance.440,441 Furthermore, histone acetylation affects DNA damage repair in cancer cells by regulating chromatin remodeling. The gene discussed is HDAC9; the disease is glioblastoma.