PTH itself is not a chemotactic factor for mesenchymal progenitors.

<p>(A) qRT-PCR quantification of mRNA levels of PTH1R in UMR106-01 cells and rat mesenchymal progenitors in culture. ***: p<0.001 vs. UMR. (B) The expression of PTH1R in rat calvarial osteoblasts increases dramatically during their osteogenic differentiation as measured by qRT-PCR. PRO: proliferation stage; DIF: differentiation stage; MIN: mineralization stage. **: p<0.01; ***: p<0.001 vs. PRO. (C) PTH stimulates cAMP production in UMR 106-01 cells but not mesenchymal progenitors. ***: p<0.001 vs. con. (D) PTH alone does not stimulate the migration of mesenchymal progenitors. Chemotaxis assays were performed with lower wells filled with αMEM, αMEM containing 10 nM PTH, conditioned media from control- and PTH-treated UMR 106-01 cells, and αMEM containing 5% FBS. ***: p<0.001 vs. CON.