HDACs are a family of proteins with diverse roles. HDAC6 is a class IIb histone that deacetylates cytoplasmic proteins, including tubulin, heat shock protein 90, and cortactin, and has roles in cell adhesion and motility.HDAC8, on the other hand, is a class I histone that primarily targets nuclear proteins, including histones and cohesins, and regulates gene expression.BRD73954 is a small molecule inhibitor that potently inhibits both HDAC6 and HDAC8 (IC50s = 36 and 120 nM, respectively).It is at least 75-fold less effective against other HDAC isoforms.At 10 µM, BRD73954 treatment results in a robust increase in acetylation of α-tubulin, a known HDAC6 substrate, but not histone H3, a substrate for HDAC1, 2, and 3, in HeLa cells.