HDAC1 and neoplasm: Resultantly, the expression level of HDAC1 and HDAC2 was only associated with Ki-67 index (HDAC1, P = 0.021; HDAC2, P = 0.044), while HDAC3 was associated with Ki-67 index (P = 0.001) and tumor size (P = 0.005) (Supplementary Table S1).