PDPN and melanoma: The morphology of A375 cells changed from a square epithelial to a spindle-shaped mesenchymal phenotype when PDPN was down-regulated, while the morphology of A875 cells changed from rhombic to rounded phenotype when PDPN was up-regulated (Fig. 1E), which suggested that the expression level of PDPN could affect melanoma cells through morphological change.