A Western blot of p-ERK, p-p38 and p-Akt secreted by mMSCs exposed to different scaffolds (CS, SCS, CCS or BCS). B. Expressions of p-ERK, p-p38 and p-Akt were normalized against the corresponding protein levels in mMSCs exposed to the CS negative control. For each protein, groups identified with the same upper case letters, lower case letters or numbers are not significantly different (P > 0.05). C and D. Alkaline phosphatase (ALP; Fig.3C) activities and alizarin red-S staining (Fig.3D) of mMSCs when cultured with biphasic mineralized collagen scaffolds (BCS) before and after the addition of U0126, SB203580 (SB) or LY294002 (LY), the respective inhibitors for ERK, p38 and Akt signaling pathways. mMSCs cultured with collagen scaffolds (CS) served as the negative control. Groups identified with the same upper case letter are not significantly different (P > 0.05).