Figure 2. Knockdown of Islet-1 inhibits proliferation and tube formation of HUVECs. A: 3-[4,5-dimethylthiazol-2-yl]-2,5- diphenyltetrazolium bromide; thiazolyl blue (MTT) assay was performed to analyze the proliferation ability of human umbilical vein endothelial cell lines (HUVECs) affected by attenuation of cellular Islet-1. Compared to negative control, insulin gene enhancer protein ISL-1 (Islet-1) siRNA inhibited the proliferation rate of HUVECs (★p<0.05). B, C: Downregulation of Islet-1 inhibited the tube formation in HUVECs in vitro. After transfection with siRNA targeting Islet-1, the number of tubes in HUVECs following RNAi was significantly lower than that of the negative control group (★p<0.05).