CCL17 and neoplasm: Maria Pia Protti and Lucia De Monte sorted out the cytokine networks in pancreatic cancer: tumor cells release TNF-α and IL-1β to induce cancer associated fibroblasts (CAFs) to secrete thymic stromal lymphocyte (TSLP) to activate resident DCs, which can release Th2 chemokines (CCL2, CCL17) to recruit Th2 cells to the tumor region, and then Th2 cells could secrete Th2 cytokines to promote M2 polarization [126].