The major focus of this study is to analyze the expression of bovine MMPs and to monitor their activity during the estrus cycle and pregnancy. During pregnancy, MMP-2 expression was detectable around 30 days but became insignificant by 60 days, then started to increase again around 90 days and reached the maximum at 250 days. The activity of MMP-2 protein changed in accordance with its expression level. As expected, the level of TIMP-2 exhibited a reverse pattern. About MMP-9, high level expression was observed as early as 30 days and gradually increase until 90 days. Then started to decrease after 250 days. Again, the sites of MMP-9 expression were similar to those of MMP-2. On the other hand, expression of TIMP-3 remained low until 90 days but showed a small and temporal increase around 250 days. In summary, expression of different MMPs were differentially regulated during estrus cycle and pregnancy. While the expression of MMP-2 was high in estrus cycle, MMP-9 slowly takes over with the progression of pregnancy. These results indicated that the luteal tissue perform distinct functions during pregnancy and estrus. Perhaps the activity of MMP-2 is required for the structural remodeling of luteum, resulting the suppression of P4 inflow from blood. On the other hand, steady maintenance of MMP-9 throughout luteal development is important for the activation of cell proliferation, maturation and angiogenesis.

Abstract
 INTRODUCTION
 MATERIALS AND METHODS
  Corpus luteum collection
  Zymography
  Hematoxylin & Eosin stein
  Immunohistochemistry (IHC)
 RESULTS
  Enzyme activity analysis of MMPs from luteum tissues
  Expression pattern of MMPs, TIMPs and PAPP-A in the luteal body of the pregnant days
  Expression position analysis of MMPs, TIMPs and PAPP-A form pregnant luteal tissues
 DISCUSSION
 CONCLUSION
 REFERENCES

• Sang-Hwan Kim(Institute of Genetic Engineering, Hankyong National University)
• Kyong-Lae Kim(Institute of Genetic Engineering, Hankyong National University)
• Ji-Hye Lee(Major in the Animal Biotechnology, Graduate School of Future Convergence Technology, Hankyong National University)
• Da-Hye Shin(Department of Animal Life and Environment science, Graduate School of Future Convergence Technology, Hankyong National University)
• Na-Hyeon Jung(Department of Animal Life and Environment science, Graduate School of Future Convergence Technology, Hankyong National University)
• Ho-Jun Lee(Institute of Genetic Engineering, Hankyong National University)
• Jong-Taek Yoon(Institute of Genetic Engineering, Hankyong National University, Department of Animal Life Science, Hankyong National University) Correspondence