{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nPLAAT4, also known as RARRES3 or TIG3, is a retinoid‐inducible tumor suppressor whose expression is tightly regulated by retinoic acid receptors and p53. Reduced PLAAT4 expression is frequently observed in several malignancies—including ovarian, head and neck, skin, and liver cancers—where its loss is associated with impaired cellular differentiation, enhanced proliferation, and metastatic potential. In contrast, certain contexts such as glioblastoma demonstrate elevated PLAAT4 levels that correlate with poorer outcomes, suggesting that its functions can be highly context‐dependent. Altered epigenetic regulation may further impact PLAAT4 expression in hepatocellular carcinoma, contributing to tumor progression."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "8"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nPLAAT4 exhibits Ca²⁺‐independent phospholipase A₁/A₂ activity—with a marked preference for PLA₁—that enables it to catalyze the hydrolysis of diverse phospholipid substrates. Through this enzymatic activity, PLAAT4 modulates phospholipid metabolism and thereby alters the acylation status of key signaling proteins, including components of the Wnt/β–catenin pathway, to limit metastasis. In some cell types, PLAAT4 also interacts with factors such as prostaglandin D₂ synthase to augment anti‐migratory signaling, highlighting its role as a modulator of cellular adhesion and motility."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "9", "end_ref": "12"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn addition to its enzymatic functions, PLAAT4 plays a critical role in promoting terminal differentiation and orchestrating apoptotic processes. In keratinocytes, PLAAT4 localizes to the plasma membrane where it associates with type I transglutaminase to drive cornified envelope formation and differentiation. Its subcellular distribution—including centrosomal localization—contributes to the inhibition of centrosome separation, disruption of microtubule dynamics, and activation of caspase‐dependent apoptotic cascades. Detailed structure–function studies have revealed that distinct N‐ and C–terminal domains govern these processes, and PLAAT4 activity has also been implicated in the cross–linking of tau protein in neurodegenerative disorders as well as in the host response to intracellular pathogens by inducing premature parasite egress."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "13", "end_ref": "22"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Lai Wei, David Kung-Chun Chiu, Felice Ho-Ching Tsang, et al. 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