{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nROBO4 is an endothelial‐specific receptor that plays a critical role in maintaining vascular integrity under stress. Activation of ROBO4 by its ligand Slit2 strengthens the endothelial barrier, reducing hyperpermeability, leakiness, and the deleterious effects of excessive inflammatory cytokines—mechanisms that have been shown to improve outcomes in sepsis, endotoxemia, and even in settings where viral proteins (such as HIV‐1 gp120) disrupt vascular homeostasis. In retinal and other microvascular beds, the Slit2–ROBO4 axis also regulates responses to hypoxia and high glucose, tempering inflammatory signaling and protecting barrier function."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "6"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn the context of angiogenesis and endothelial cell dynamics, ROBO4 modulates cell migration, cytoskeletal rearrangement, and tube formation. Studies have demonstrated that ROBO4 can interact directly with intracellular adaptor molecules—such as paxillin, WASP complexes, and GIT1—to curb excessive protrusive activity and to fine‐tune angiogenic sprouting. Moreover, ROBO4 often works in concert with ROBO1 (forming heterodimeric complexes) to regulate filopodia formation and directional migration, a process that impacts tumor vascularization and the development of stable vascular networks in engineered tissues."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "7", "end_ref": "14"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nROBO4 expression is tightly controlled via transcriptional and epigenetic mechanisms, ensuring its endothelial‐restricted and context‐dependent function. Promoter studies have highlighted the importance of binding motifs for transcription factors such as SP1, GABP, and AP‑1 in directing ROBO4 gene expression. Disruptions or genetic variants in ROBO4—with implications in congenital cardiovascular anomalies (for example, bicuspid aortic valve/ascending aortic aneurysm), diabetic retinopathy, and even tumor progression—underscore its clinical relevance. In several malignancies, altered ROBO4 levels correlate with aberrant vascular remodeling and therapy resistance, and its expression is emerging as a potential biomarker for vascular stabilization and disease prognosis."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "15", "end_ref": "26"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Nyall R London, Weiquan Zhu, Fernando A Bozza, et al. 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