Suberoylanilide hydroxamic acid (SAHA) is a class I and class II histone deacetylase (HDAC) inhibitor. It is a fluorescent probe that competitively binds HDAC. It is a SAHA derivative where the anilino “cap” group is replaced by 7-amino-4-methylcoumarin. The fluorescence excitation and emission maxima of free c-SAHA is 325 and 400 nm, respectively. Fluorescence is quenched by 50% when bound to HDAC8.