CXCL9 and melanoma: To determine whether CXCL9-expressing ECs promote the TEM of melanoma cells, HUVECs were either transfected with pIRES-EGFP-CXCL9 plasmid, mock transfected or non-transfected and subsequently seeded onto fibronectin-coated Transwell culture chambers until confluent monolayers were formed.