KLF4 and neoplasm: To further demonstrate whether it was H2O2-induced overexpression of KLF4 that caused endothelial cell senescence, we overexpressed KLF4 on normal HUVECs, which demonstrated that HUVECs overexpressing KLF4 showed similar phenotype (Fig. 5A, B) and tumor-promoting migration ability (Fig. 5C, D, E) to H2O2-induced senescent HUVECs, and then we further knocked down KLF4 in senescent HUVECs, and the senescent HUVECs lost their senescent phenotypes (Fig. 5F, G) and tumor-promoting migration ability (Fig. 5H, I, J).