The class I o-aminoanilide HDAC inhibitor CI-994 was conjugated to the VHL ligand via a twelve-carbon alkyl linker to synthesize a PROTAC with a DC50 of 1 μM for HDACs 1, 2 and 3 in HCT116 human colon cancer cells. Here, HDAC9 is linked to malignant colon neoplasm.