PTGS2 and neoplasm: DCs form an integral part of the tumor microenvironment owing to their ability to prime and regulate T cells.355 DC-regulating compounds such as PGE2, which strongly influences DC maturation and function, can have a pronounced impact on the local niche.3,356 Using a lung parenchymal tumor model generated through the direct injection of GFPV-transfected LLC cells in the soft tissue of the left lung, Ogawa et al.92 determined that at 1 to 3 days post-tumor implantation, regional LNs harbored COX-2-positive cells in the subcapsular region.