Expression of the plasminogen activator (PA) and PA inhibitors in the mouse uterus during the estrus cycle. (A) Real-time PCR was conducted to evaluate gene expression levels. Relative levels of mRNA were normalized to Hprt mRNA levels. Data are presented as the mean of four individual experiments, and error bars represent the standard deviation (SD). a Significant difference compared to other Serpin mRNA levels (p < 0.05). b Significant difference compared to Plau mRNA levels (p < 0.001). (B) Expression of the SERPINE2 protein in the cycling uterus. Forty-five micrograms of total protein prepared from the homogenates of uterine tissue at proestrus (P, lane 2), estrus (E, lane 3), metestrus (M, lane 4), and diestrus stages (D, lane 5) was analyzed by Western blotting. The purified SERPINE2 protein (30 ng) was loaded as the positive control (lane 1). 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.