Figure 9D-F. Effect of MSDK on MAPKs, ERK1/2 and ERK5. (D) ERK5 expression of osteoblasts and osteoclasts grown in layered co-culture, (E) ERK5 expression of osteoblasts in hMSCs mono-culture and (F) phospho-ERK5 expression of osteoclasts grown in transwell co-culture. Cell lysates were prepared on day 21 from the bottom (osteoblasts) and top (osteoclasts) chambers in the transwell co-culture and from the whole plate (both osteoblast and osteoclast) in the layered co-culture. Protein levels were normalized against β-actin and then to Os-/MSDK. Mean expression of (i) phospho-ERK: total-ERK (ii) phospho-ERK (iii) total-ERK in each co-cultures were analyzed and compared between groups (Os-/MSDK, Os+/Veh, Os+/MSDK). *=p<.05, **=p<.01 and **=p<.001; One-way ANOVA followed by Bonferroni’s post-hoc multiple comparison t-test (n=6 per group).