SB-429201 is a potent and selective HDAC1 (IC50~1.5 μM). SB-429201 displays at least a 20-fold preference for HDAC1 inhibition over HDAC3 and HDAC8[1][2].
[1]. Hu E, et al. Identification of novel isoform-selective inhibitors within class I histone deacetylases. J Pharmacol Exp Ther. 2003;307(2):720-728. [2]. Bieliauskas AV, Pflum MK. Isoform-selective histone deacetylase inhibitors. Chem Soc Rev. 2008;37(7):1402-1413.