CD4 and Patent ductus arteriosus: Though obvious CD4, CD8 and Foxp3 expression were not observed in normal pancreatic tissue, Foxp3 was strongly expressed in the tumor stroma, with more Foxp3+ cells have been observed in the PDA juxtatumoral stroma than in the PDA panstroma (P = 0.0043, R = 0.02217) (Figure 3).