Expression of Serpine2 mRNA and protein in the placenta. (A) Placental expression of Serpine2 mRNA. Quantitative real-time PCR was conducted to analyze gene expression levels. The relative levels of mRNA were normalized to Hprt mRNA levels. Data are presented as the mean of three individual experiments, and error bars represent the standard deviation (SD). a Significant difference compared to Serpine2 mRNA levels (p < 0.001). b Significant difference compared to Plau mRNA levels (p < 0.001). (B) Placental SERPINE2 expression. Forty-five micrograms of total protein prepared from the homogenates of placental tissue was analyzed by Western blotting. The arrowhead indicates a possible protein complex of SERPINE2 and a certain protease. Arrows indicate the isoform proteins of SERPINE2. The α-tubulin protein level is shown as the loading control.