English: Tube formation assay was performed using the BD BioCoat Angiogenesis System-Endothelial Cells Tube Formation Matrigel Matrix 96-well plate as described in the Materials and Methods. U87 conditioned media (CM) were prepared by incubating cultures with medium alone (Ctr), IL-1β (10 ng/ml), or IL-1β plus IL-1ra (1 µg/ml). HUVEC at 2.5×104 cells were suspended in U87 CM and then added to the plates for 18 h at 37°C. Cells were then fixed in 4% PFA and viewed by phase-contrast microscopy. (A) Representative photography. (B) The number of closed network of vessel-like tubes was counted from three experiments. Data are mean ± SD ***p<0.001.