In vivo rodent model of PPBC: injecting DCIS-GFP, D2A1, or 66cl4-LUC cells into mammary fat pad of SCID or BALC/c mice on INV1. Lymphatic vessel density by LYVE1 +vessel count and mRNA gene expression levels. COX-2 knock down cells injected into postpartum host. The gene discussed is PTGS2; the disease is ductal breast carcinoma in situ.