Dickkopf (DKK)-1 suppresses prostaglandin endoperoxide synthase (PTGS)-2-induced macrophage and neutrophil recruitment to lung metastases by antagonizing cancer cell non-classical WNT/Planar cell polarity (PCP)-RAC1-JNK signaling, whereas it encourages breast-to-bone metastasis by modulating classical WNT signaling of osteoblasts (99). Here, PTGS2 is linked to cancer.