Fig. 1.

CD99 expression during osteoblast differentiation in hBM-MSCs (A) and human osteoblasts (hOBs) (B). For both cultures, expression of specific markers of differentiation in RT-PCR are shown. Relative expression of alkaline phosphatase (ALP) or osteocalcin (OCN) mRNA was calibrated on undifferentiated cells at day 0 (2^-ΔΔCT = 1). Data are presented as mean ± SEM of experiments performed in triplicate. Student's t test was used (*p < 0.05; **p < 0.01). Alizarin Red S (ARS), ALP, and von Kossa stainings were performed as described in Materials and Methods to evaluate cellular differentiation and matrix mineralization. CD99 expression was detected by Western blotting.