Effects of TGF-β1 and BMP-7 on SZP in the muscle-derived mesenchymal progenitor/stem cells (MDMSCs). Primary cells were cultured for 3 days (A and D), 7 days (B and E) and for 10 days (C and F) as a monolayer in serum-free conditioned medium with TGF B1 (3 ng/ml) and BMP-7 (300 ng/ml). SZP in the medium was quantified by enzyme-linked immunosorbent assay (ELISA) and SZP mRNA induction was assessed using quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR). Values were represented by the means ± standard deviations. A significance level of P < 0.05 was used to determine the differences between the control and treated cells.