mRNA expression. The mRNA levels of (A) heat-shock proteins (HSP)27, (B) HSP70, (C) HSP90, (D) BMP2, (E) Smad1, (F) Smad5, and (G) OSX were measured from total RNA extracted from the osteoblasts of 24-h culture. mRNA expression levels are expressed as fold difference of value in the groups to value in control without Noggin (−). Data are expressed as mean ± SD (n = 3). a, versus control without Noggin (−) and b, versus control with Noggin (+). a, b, and *: p < 0.05 was recognized to be significant.