In subconfluent endothelial cells, interaction of VEGF with its type-2 receptor (VEGFR2) activates the MAPK pathway. MAPK (ERK1/2) phosphorylates VEGFR2 as well as transcription factors that stimulate uPAR synthesis. The phosphorylated VEGFR2 induces detachment of β-catenin from nearby VE-cadherin, thus promoting cell proliferation. Therefore, sparsely seeded endothelial cells show VEGF-dependent uPAR up-regulation with a strong increase of invasion and are provided with free β-catenin available for nuclear translocation, while the density-enhanced phosphatase-1 (DEP-1) is scarcely represented. Overall, these features foster endothelial-cell migration and growth. In confluent endothelial cells VEGFR2, VE-cadherin, and overexpressed DEP-1 undergo junction clustering. The presence of overexpressed DEP-1 impairs MAPK activation, thereby inhibiting uPAR synthesis and VEGFR-2 phosphorylation. The growth-inhibitory effects are believed to be mediated by the capacity of VE-cadherin to link β-catenin at the membrane, limiting in this way its nuclear translocation. Coupling growth inhibition with low uPAR levels results in exhaustion of the angiogenesis program.

In subconfluent endothelial cells, interaction of VEGF with its type-2 receptor (VEGFR2) activates the MAPK pathway. MAPK (ERK1/2) phosphorylates VEGFR2 as well as transcription factors that stimulate uPAR synthesis. The phosphorylated VEGFR2 induces detachment of β-catenin from nearby VE-cadherin, thus promoting cell proliferation. Therefore, sparsely seeded endothelial cells show VEGF-dependent uPAR up-regulation with a strong increase of invasion and are provided with free β-catenin available for nuclear translocation, while the density-enhanced phosphatase-1 (DEP-1) is scarcely represented. Overall, these features foster endothelial-cell migration and growth. In confluent endothelial cells VEGFR2, VE-cadherin, and overexpressed DEP-1 undergo junction clustering. The presence of overexpressed DEP-1 impairs MAPK activation, thereby inhibiting uPAR synthesis and VEGFR-2 phosphorylation. The growth-inhibitory effects are believed to be mediated by the capacity of VE-cadherin to link β-catenin at the membrane, limiting in this way its nuclear translocation. Coupling growth inhibition with low uPAR levels results in exhaustion of the angiogenesis program.

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