Pharmacological inhibition of HDAC6 and USP9X using ACY738, a blood‐brain barrier‐permeable HDAC6 inhibitor, and WP1130 also suppressed GBM cell growth and induced apoptosis (Figure5A–F) at concentrations that did not affect normal cell viability (Figure S6, Supporting Information). Here, HDAC6 is linked to glioblastoma.