OPN acts as an important protein to promote cell adhesion on the surface of C-SR.

<p>(A) Western blots results show the expression level of OPN secreted from dermal fibroblasts cultured on SR or C-SR coated 6-well plate (48 hours). Note that OPN was up-regulated and secreted from dermal fibroblasts cultured on C-SRs. (B) Immuno-fluorescence images show that the expression level of OPN in dermal fibroblasts cultured on C-SR coated 6-well plate was increased (48 hours). (C) FITC-labeled actin tracer results demonstrate that exogenously-added purified OPN (0.5 µg/ml) enhanced dermal fibroblasts adhesion and proliferation. On the other hand, the monoclonal antibody against OPN inhibited dermal fibroblasts adhesion and proliferation on the surface of C-SRs (48 hours). (D) Cell adhesion on different substrates. OPN promoted fibroblasts adhesion, and monoclonal antibody against OPN significantly inhibited cell adhesion. However, the difference was not statistically significant when the substrate in group (OPN− Anti-OPN−) was respectively compared to the substrate in group (OPN+ Anti-OPN−) or group (OPN− Anti-OPN+) (p>0.05). The difference was significant between the substrates in group (OPN+ Anti-OPN−) and group (OPN− Anti-OPN+) (*p<0.05). These experiments were repeated three times, similar results were obtained each time (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098320#pone-0098320-g004" target="_blank">Fig. 4A</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098320#pone-0098320-g004" target="_blank">Fig. 4B</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098320#pone-0098320-g004" target="_blank">Fig. 4C</a>). Bar = 20 µm. The cell adhesion test was performed six times, the data are expressed as mean ± SD (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098320#pone-0098320-g004" target="_blank">Fig. 4D</a>).