Fig. 5

EPCs induce osteogenic differentiation by promoting MAPK phosphorylation. MSCs were pretreated with p38 signaling inhibitor SB203580, ERK signaling inhibitor FR 180204, or JNK signaling inhibitor SP600125 and then co-cultured with EPCs and examined for a the protein levels of p-p38, p38, p-ERK1/2, ERK1/2, p-JNK, and JNK by immunoblotting. b Scanning densitometry of relative protein levels of p-p38, p38, p-ERK1/2, ERK1/2, p-JNK, and JNK by immunoblotting, β-actin was used as the internal control. Data are presented as the mean ± SD, *p < 0.05. c Osteogenic differentiation was determined by ALP staining. d Calcium nodules formation was determined by Alizarin Red staining. e Relative ALP activity (n = 3), *p < 0.05. f Relative mineralization levels (n = 3), *p < 0.05