HDAC9 and neoplasm: In addition, when the patients were grouped according to their overall class I HDAC expression pattern (all three isoforms negative versus one or two isoforms positive versus all three isoforms positive), positive expression of all three isoforms was associated with enhanced Ki-67 index as a surrogate marker of proliferation (P<0.001, one way ANOVA) and tumor size >5 cm (P = 0.033, χ2 test for trends; Supplementary Table S1).