The invention relates to the inhibition of histone deacetylase. The invention provides compounds and methods for inhibiting histone deacetylase enzymatic activity. The invention also provides compositions and methods for treating cell proliferative diseases and conditions. One aspect of the invention provides compounds of formula (1):in which T, A and X are as described herein.本發明係關於組織蛋白去乙醯基酶之抑制作用。本發明提供用於抑制組織蛋白去乙醯基酶酶促活性之化合物及方法。本發明亦提供用於治療細胞增生性疾病及病狀之組合物及方法。本發明之一態樣提供式(1)化合物:其中T、A及X如本文中所述。