Table 1.

HDAC isoforms and main used of pan-HDAC inhibitors.

Histone subtype	Protein	Localization	Main HDAC inhibitors
Class I (Zn++-dependent)	HDAC1, 2, 3, and 8	Mainly nucleus	Valproic acid, butyrate, vorinostat, trichostatin A, RGFP136 (HDAC3)
Class IIa (Zn++-dependent)	HDAC4, 5, 7, and 9	Nucleus/cytoplasm	Trichostatin A, phenylbutyrate
Class IIb (Zn++-dependent)	HDAC6 and 10	Mainly cytoplasm	Tubacin (HDAC6), trichostatin A
ClassIII (NAD+-dependent)	SirT1, 2, 3, 4, 5, 6, and 7	Nucleus/cytoplasm/Mitochondria	Nicotinamide, suramin (SirT1 and SirT2),
Class IV (Zn++-dependent)	HDAC11	Mainly nucleus