Rabbit and murine BM cells cocultured with Postn siRNA OP9 or GFP siRNA OP9 cells. (A) SqRT-PCR for Postn in stable transfectants of GFP siRNA OP9 and Postn siRNA cells (left). QRT-PCR for Postn and IL-7 in OP9, OP9-309, and OP9-309P cells; expression levels were normalized to Hgprt housekeeping gene (similar results were obtained in 2 independent experiments; middle). Flow cytometric analysis of OP9 and OP9-309 cells stained with anti–periostin Ab (right). (B-C) Total number of nonadherent cells harvested 1 and 2 weeks after coculture of 10 000 total rabbit (B) and murine (C) BM cells with GFP siRNA OP9 and Postn siRNA OP9 (OP9-309) cells. Error bars are SEM from triplicate wells. Results are representative of 3 experiments.