{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n ARHGAP17 is emerging as a versatile regulator of Rho family GTPase signaling with important roles in diverse cellular contexts. In platelets, ARHGAP17 acts as a Rac1‐specific GTPase–activating protein whose phosphorylation at serine 702 by cyclic nucleotide–dependent kinases alters its interaction with the actin‐regulatory protein CIP4, thereby modulating Rac1 activity and suppressing cell migration."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": " \n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In epithelial cells, ARHGAP17 (also known as Rich1 or NADRIN) negatively regulates CDC42 and RAC1 signaling. Its up‐regulation can lead to S‐phase arrest, reduced proliferation, altered cell adhesion, and is essential for maintaining tight junction integrity and barrier function; indeed, ARHGAP17 deficiency in intestinal epithelium results in increased paracellular permeability and mislocalization of the apical junctional complex."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": " \n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In cancer cells, ARHGAP17 exhibits tumor‐suppressive functions. In cervical cancer, reduced ARHGAP17 expression correlates with enhanced PI3K/AKT signaling and increased proliferation, while its overexpression elevates cell cycle inhibitors and inhibits tumor growth."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "4"}]}, {"type": "t", "text": " Similarly, in colon cancer, ARHGAP17 suppresses malignancy by attenuating Wnt/β‐catenin signaling, thereby reducing β‐catenin nuclear translocation and downstream oncogenic effects, and it further sensitizes chemoresistant cells to apoptosis induced by 5‐fluorouracil."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": " \n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Moreover, tissue‐specific isoforms of ARHGAP17 broaden its functional repertoire. A brain‐specific splice variant, BARGIN, binds polyubiquitin, thereby promoting its membrane localization and mediating localized Rac1 inactivation—a mechanism that may have implications in neurodegenerative conditions."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": " In astrocytes, up‐regulation of ARHGAP17 facilitates stellation and morphological differentiation through RhoA inactivation via associations with ERM proteins."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "8"}]}, {"type": "t", "text": " Finally, in human periodontal ligament fibroblasts, overexpression of ARHGAP17 protects against mechanical stress–induced apoptosis by dampening Rac1/Cdc42 activation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Collectively, these studies highlight that ARHGAP17, through modulation of small GTPase activities, plays a critical role in controlling cell proliferation, migration, differentiation, and barrier integrity in a cell type–specific manner.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Zoltan Nagy, Kieran Wynne, Alexander von Kriegsheim, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "Rich1 negatively regulates the epithelial cell cycle, proliferation and adhesion by CDC42/RAC1-PAK1-Erk1/2 pathway."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Cell Signal (2015)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.cellsig.2015.05.009"}], "href": "https://doi.org/10.1016/j.cellsig.2015.05.009"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "26004135"}], "href": "https://pubmed.ncbi.nlm.nih.gov/26004135"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "So-Young Lee, Hwain Kim, Kyoungmi Kim, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Arhgap17, a RhoGTPase activating protein, regulates mucosal and epithelial barrier function in the mouse colon."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Sci Rep (2016)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/srep26923"}], "href": "https://doi.org/10.1038/srep26923"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "27229483"}], "href": "https://pubmed.ncbi.nlm.nih.gov/27229483"}]}, {"type": "r", "ref": 4, "children": [{"type": "t", "text": "Qisang Guo, Ying Xiong, Yu Song, et al. 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