Fig. 4. RUNX2 promotes the expression of Htra1 in primary mesenchymal progenitor cells (A-C) Relative mRNA expression of Runx2 (A), Htra1 (B), and Sp7 (C) at d8 during osteogenic differentiation of primary mesenchymal progenitor cells after overexpression of Runx2. (D-G) Western blot analyses of RUNX2 (D, E) and HTRA1 (F, G) at d8 during osteogenic differentiation of primary mesenchymal progenitor cells after overexpression of Runx2. Immunoblots (D and F) and densitometric analyses (E and G) show increase in RUNX2 and HTRA1 protein with the overexpression of Runx2. Densitometry data (n=3 biological replicates) were normalized to β-ACTIN and represented relative to empty vector control (mean±S.E.M; Two-tailed unpaired T-test, *p<0.05, **p<0.01; ***p<0.001).