Sp1 knockdown by siRNA in hFOB and Saos2 cells reduces FZD1 expression and osteoblast differentiation.

<p>(A) Western blot analysis of Sp1 and FZD1 expression in hFOB cells transfected with 50 nM Sp1 siRNA or scramble siRNA as a control. (B) Real-time quantitative PCR for Sp1, FZD1 and osteoblast differentiation associated genes in hFOB cells transfected with 50 nM Sp1 siRNA or scramble siRNA as a control. (C) ALP activity staining with BCIP/NBT substrate solution (Sigma, USA) in Saos2 and hFOB cells transfected with 50 nM Sp1 siRNA or scramble siRNA. (D) Quantitative results of the ALP staining for Fig 4C by densitometry. All siRNA knockdown experiments were conducted in triplicates and repeated for 2 independent times. * indicates significant difference between the control siRNA and Sp1 specific siRNA treated cells (<i>P</i> < 0.05).