Fig. 7.

Schematic diagram of the EphB4, TNFR2 and ERK/MAPK signaling pathways. A low concentration of TNF-α first enhances the expression of EphB4, which in turn promoted the expression of TNFR2. The elevated TNFR2 level leads to the activation of the ERK signaling pathway, which eventually enhances the osteogenic differentiation of MC3T3-E1 cells. TNFR2, tumor necrosis factor receptor 2; TNF-α, tumor necrosis factor-alpha; MAPK, mitogen-activated protein kinase; ERK, extracellular signal regulated kinase