FIG. 4.

Role of PDGFR-β in TGF-β1 signaling. (A) Flow cytometric analysis of surface PDGFR-β expression on MSCs in response to soluble factor treatment at 24 h. (B, C) Percent positive population and MFI of treated cells were calculated from FACS-DIVA. PDGF and combination of PDGF and TGF-β1 resulted in reduced available surface receptors after 24 h; TGF-β1 treatment also reduced available PDGFR-β. Results are reported as average±SEM (n=3). (D) Effect of small-molecule chemical inhibitors SB-505124 (blocks TGF-βRI-mediated signaling) and JNJ-10198409 (inhibits PDGFR-β-mediated signaling) on the viscoelastic properties of soluble-factor-treated MSCs were evaluated after 24 h. The average mean squared displacements of 100-nm particles embedded in the cytoplasm of cells and frequency-dependent elastic (G′) and viscous (G′′) moduli of inhibitor-treated MSCs were similar to the control cells (Fig. 2A, B). Statistical significances are indicated as (*) for p<0.05, (**) for p<0.005, and (***) for p<0.0005.