Several studies have investigated the interactions between tumor cells and endothelia cells and identified a few related molecules, including runt-related transcription factor 2 (RUNX2), osteopontin (OPN), urokinase-type plasminogen activator (uPAR), and formyl peptide receptor type 1 (FPR1), all of which are further shown to facilitate metastasis in vivo. The gene discussed is SPP1; the disease is neoplasm.