three isoforms. Most likely, ECs primarily express Stabilin-1 and -2 that are 7.8 and 6.2 kbs isoforms respectively. The GAPDH probe was included as a control for the quantity and integrity of the loaded RNA, detecting a single transcript of ~1.3 kb. All data shown are representative of those obtained in at least three separate experiments, with similar results. Figure 2. Northern confirmation of KDR, ? 2 integrin subunit, VE-cadherin, MMP1, and MMP2 during activation of ECs. ECs were cultured in 3D collagen matrices with VEGF 165 . At various time points (indicated), total RNA was isolated and analyzed by Northern blot, as described in the "Methods". Blots were hybridized with indicated 32 P-radiolabeled probes. PCR primers used to generate probes are shown in Table II . Data shown are representative of those obtained in two or three separate experiments, with similar results. Figure 3. Northern blot confirmation of VEGF-responsive genes. ECs were cultured in 3D collagen matrices with (+) or without (-) VEGF 165 . After 24 hours, total RNA was isolated and analyzed by Northern blot, as described in the "Methods". The 32 P-radiolabelled probes used and their corresponding GenBank accession numbers are indicated, and abbreviated gene names are given in perentheses (also see Table I ). The GAPDH probe was included as a control for the integrity and loading of the total RNA. Blots are representative of those obtained in two or three separate experiments, with similar results. Confirmation of Differentially Expressed Genes by Western Blot To