... available at the end of the article Kumagai et al. AMB Express 2011, 1:23 http://www .amb- express. com/content/1/1/23 © 2011 Kumagai et al; licensee S pringer. This is an Open Access article distributed ... shown in the polygonal line graph. Data represent thegeometric mean ± standard deviation of duplicate determinations. Kumagai et al. AMB Express 2011, 1:23 http://www .amb- express. com/content/1/1/23 Page ... (Kojima et al. 1991,;Yaoita et al. 1990,), gene expression of nerve growth fac-tor (Koyama et al. 1996,; Koyama et al. 1997,) andneural and osteogenic differentiation (Kimura et al. 1998,; Mie et...