{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nRhoH is an atypical, hematopoietic‐specific small GTPase that, despite lacking intrinsic GTPase activity, functions as a critical adaptor protein in antigen receptor signaling. In T lymphocytes, RhoH orchestrates thymocyte development and maturation by facilitating the recruitment and activation of key kinases—most notably ZAP70 and Lck—at the immunological synapse. Through regulation of early T cell receptor (TCR) signaling events, RhoH ensures effective β‐selection, positive selection, and peripheral T cell function, with its altered expression impacting responses such as alloreactivity in transplantation contexts."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "6"}]}, {"type": "t", "text": "\n\nDiscretion in RhoH function extends to hematopoietic progenitor cells and innate immune effectors where it modulates cytoskeletal dynamics and Rac1‐mediated signaling. In progenitors, RhoH acts as a negative regulator of proliferation, survival, and chemotaxis—thus balancing actin polymerization and directional migration responses to chemokine cues. In neutrophils, RhoH is induced following inflammatory stimuli and serves as a feedback inhibitor that limits degranulation, the formation of extracellular traps, and mitochondrial transport by tempering actomyosin interactions, thereby fine‐tuning antibacterial responses."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "7", "end_ref": "10"}]}, {"type": "t", "text": "\n\nMoreover, RhoH regulates signaling in other hematopoietic lineages. In mast cells, it facilitates Syk activation and subsequent degranulation and cytokine release upon FcεRI engagement. In eosinophils, RhoH expression modulates differentiation—likely by influencing transcription factors such as GATA‐2—thus controlling eosinophil production. 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