Aim To explore effects of oxidized low density lipoprotein(ox-LDL) and mechanical stretch stress(SS) on activation of extracellular regulated kinase(ERK1/2) in macrophage RAW264.7 cells. Methods The cultured RAW264.7 cells were identified via ink staining.Agarose gel electrophoresis was employed to identify and quantitate ox-LDL which was oxidated from n-LDL with copper sulfate.The identified RAW264.7 cells were subjected to treatment with ox-LDL and SS,respectively or jointly,for different dose/elongation and time duration,and then the phosphorylation of ERK1/2 in the macrophages was detected by Western blotting. Results RAW264.7 cells could phagocytize ink,forming cloudy ink plaque or black particles in cytoplasm.N-LDL could be oxidized into ox-LDL by copper sulfate,since a single lane about ox-LDL could be seen in agarose gel electrophoresis,and the electrophoretic mobility of ox-LDL was higher than that of n-LDL,indicating successful ox-LDL preparation.Ox-LDL and SS could induce ERK1/2 phosphorylation,respectively,in a time and dose dependent manner,and dramatical increase of ERK1/2 phosphorylation was observed when the cells were co-treated with SS and ox-LDL. Conclusions Ox-LDL and SS could induce ERK1/2 phosphorylation,and combined treatment of ox-LDL and SS could synergistically promote ERK1/2 phosphorylation in macrophages.This study could provide useful information for exploring the roles of macrophages and its mechanism in hypertension-related atherosclerosis.