HDAC9 and thyroid gland papillary carcinoma: Low acetylated levels of different histones in tumor tissues in comparison with the adjacent normal tissues in this study may also reflect an active status of HDACs in papillary thyroid cancer, though the level of HDAC in tumor tissues seems not change significantly in comparison with that of normal tissues by global proteomics (Ca-T/ Ca-N, 0.937 in histone deacetylase and 1.065 in histone deacetylase complex subunit SAP18, respectively).