PTGS2 and major depressive disorder: If the results from basic study support the hypothesis of the role of COX2 in depression and the role of PLA2 in CVD, we will be able to take the step further into genetic studies and explore whether (1) mice of knockout cPLA2 genes would have increased the risk of CVD, since more studies have focused on cPLA2 gene polymorphism and its association with depression; and whether (2) mice of knockout COX2 genes would have increased depression-like behaviors in animal models.