PDPN and cancer: An SZ163/SZ168-double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed to quantitate plasma-soluble PDPN in cancer patients and evaluate the correlation between PDPN and tumor occurrence and metastasis [24], although it is unknown whether SZ163 and SZ168 inhibit the growth and metastases in PDPN-expressing human tumors.