Abstract: Objective To detect the expression of EGF containing fibulin-like extracellular matrix protein 1(EFEMP1) in thetissues and cell lines(F4 and F5M2) of osteosarcoma,and explore the its role in promoting the invasion and migrationof human osteosarcoma. Methods The expression of EFEMP1 in tumor tissue of 45 cases of osteosarcoma and 12 cases of osteochondroma were detected by using immunohistochemical SP method;the expression of EFEMP1 protein and mRNA in F4 and F5M2 cell lines was detected by using Western-blot and quantitative Real Time PCR,respectively.The effects of EFEMP1 on the invasion and migration of F5M2 cells were investigated by Transwell methods. Results EFEMP1 was expressed in 93.3%(42/45) of osteosarcoma tissues,strongly positive in 64.4%(29/45),3(6.7%) negative cases,and negative in all osteochondroma tissues.Western-blot and quantitative Real Time PCR showed that EFEMP1 was expressed differently in the human osteosarcoma cell line F4 and F5M2,F5M2 cells had a higher level(P＜0.05).Transwell test showed that the invasion and migration of F5M2 cells in the experimental group were increased,prompting that recombinant human EFEMP1 protein can stimulate the migration and invasion of F5M2 in vitro(P＜0.05). Conclusion EFEMP1 highly expressed in the human osteosarcoma tissues and cell lines F5M2 and F4 (expression levels in F5M2 exceed F4).The recombinant human EFEMP1 protein can stimulate the invasion and migration of human osteosarcoma.To detect the expression of EFEMP1 will provide a new strategy for early diagnosis and therapy for osteosarcoma patients.