HDAC6-IN-48 (compound 5i) is a potent and selective HDAC6 inhibitor with IC 50 values of 5.16, 396.72, 638.08 nM for HDAC6 , HDAC3 , HDAC1 , respectively. HDAC6-IN-48 induces apoptosis and cell cycle arrest at G0/G1 phase. HDAC6-IN-48 increases the protein expression of acetylated α-tubulin.