Fig. 4

Alkaloid extract of YHS blocked VEGFR2 signaling pathway (a) Western blot bands for phosphorylation of VEGFR2 and total VEGFR2 in HUVECs lysates 24 h following various concentrations of alkaloid extract of YHS treatment in the absence or presence of VEGF. β-actin was used as a loading control. b Densitometric ratios for VEGFR2 activities were quantified. Data are presented as the normalized expression of mean of three independent HUVEC lines ± SEM. ***, P < 0.001; **, P < 0.01; *, P < 0.05, paired t-test. c Western blot bands for phosphorylation of AKT, ERK, STAT3 and total AKT, ERK, STAT3 in HUVECs lysates 24 h following various concentrations of alkaloid extract of YHS treatment in the absence or presence of VEGF. β-actin was used as a loading control. Densitometric ratios for AKT (d), ERK (e) and STAT3 (f) activities were quantified. Data are presented as the normalized expression of mean of three independent HUVEC lines ± SEM. ***, P < 0.001; **, P < 0.01; *, P < 0.05, paired t-test. g Immunofluorescence of STAT3 (green) in HUVECs following exposure to (b) 0 μg/ml; (c) 10 μg/ml; (d) 50 μg/ml; (e) 100 μg/ml of alkaloid extract of YHS in the presence of VEGF. Translocation of STAT3 in non-treated HUVECs is shown as control (a). Nuclei were counterstained with DAPI (blue), scale bar: 50 μm