Angiogenesis is crucial in wound healing.The administration of the C-terminal 24-a.a.peptide of mechano growth factor (MGF24E) has been previously demonstrated to induce more blood vessels in regenerating bone around defective areas compared with the control.Accordingly,this study aims to determine whether MGF24E promotes bone defect healing through MGF24E-increased angiogenesis and whether MGF24E has positive effects on angiogenesis in vitro.The roles of MGF24E on angiogenesis and the underlying mechanisms were investigated.The cell proliferation,migration,and tubulogenesis of the human vascular endothelial EA.hy926 cells co-treated with 2％ serum and MGF24E were determined to assess angiogenesis in comparison with 100 ng/ml of vascular endothelial growth factor 165 (VEGF16s)-positive control or vehicle control (phosphate-buffered saline).MGF24E treatment (10 ng/ml) significantly promoted the biological processes of angiogenesis on EA.hy926 cells compared with the vehicle control.The suppression of vascular endothelial growth factor and angiopoietin-I expressions by 2％ serum starvation was reversed by the addition of 10 ng/ml of MGF24E in 2％ serum medium.This result suggests that MGF24E has a protective effect on angiogenesis.Moreover,the inhibition of ERK due to PD98050 pretreatment completely abolished and mostly blocked MGF24E-induced proliferation and migration,respectively,whereas the MGF24-induced tubulogenesis and the angiogenic factor expression were only partially inhibited.These new findings suggest that MGF24E promotes angiogenesis by enhancing the expression of angiogenic cytokines which involves the MAPK/ERK-signaling pathway.