Role of class IIa HDAC isoenzymes for angiogenic function and cell-cycle progression in endothelial cells. (A-F) Effects of siRNA against individual class IIa HDAC isoenzymes in HUVECs on (A) HDAC mRNA expression as measured by quantitative PCR. Data (delta Ct) are mean ± SEM (n = 3, *P < .05 vs scrambled). (B) Capillary-like sprout formation from spheroid cultures (n ≥ 4; *P < .05). (C) Scratched wound endothelial cell migration (n ≥ 3; *P < .05). (D) Proliferation rate measured by flow cytometric detection of BrdU-labeled HUVECs in the S-phase (n = 7-11). (E) Viability measured by MTT assay (n = 3). (F) Tube formation in a Matrigel assay (n = 6; *P < .05). (G-K) Biochemical and histologic analysis of Matrigel plugs containing scrambled versus HDAC5 siRNA-transfected HUVECs at day 7 after subcutaneous implantation (n ≥ 3 per group). (G) Representative hematoxylin and eosin–stained plug sections. Pictures were taken using an Axiovert 100M microscope, an AxioCam camera, a Plan-NEOFLUAR 10×/0.30∞/0.17 objective, and the AxioVision Rel. 4.6.3 Sp1 software (Carl Zeiss). (H) Number of invaded cells per hematoxylin and eosin–stained plug section (*P < .05). (I) Number of CD31⁺ structures per plug section. (J) Number of lectin⁺ structures per plug section. (K) Hemoglobin content of Matrigel plugs (* P < .05).