CD13/APN rescues endothelial invasion in the presence of Ras/MAPK or PI-3K inhibition.

(A) CD13/APN is required for migration/invasion. Primary endothelial cells (HUVEC) in 1% serum in the presence or absence of the indicated CD13/APN functional antagonists or vehicle or isotype-matched control antibodies were plated in the top chamber of Matrigel-coated transwell plates and bFGF angiogenic stimulus was placed in the bottom chamber. The number of cells invading and migrating through the Matrigel barrier in response to bFGF was counted after 24 hours. (B) Increased cell surface CD13/APN enhances endothelial invasion and can overcome inhibited migration/invasion. EOMA engineered to express high (20-fold) levels of CD13/APN (EOMA-CD13, ▪) or vector control cells (EOMA-pcDNA, ░) were plated in the top chamber of Matrigel-coated transwell plates in the presence of the indicated Ras, MEK, or PI-3K inhibitors, and bFGF angiogenic stimulus was placed in the bottom chamber. The number of cells invading and migrating through the Matrigel barrier in response to bFGF was counted after 24 hours. Error bars in each panel indicate standard deviation of results of at least 3 replicates.