PTGS2 and infection: For instance, it has been shown that L. donovani and L. major induced remarkably similar gene expression profiles in murine bone marrow-derived macrophages at 24h post-infection, although L. donovani induced higher expression levels of some genes (e.g., Ptgs2/COX2, prostaglandin E synthase, matrix metalloprotease 13, metallothionein 1 and 2) [9].