{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nMAPK15, also known as ERK8 (or ERK7), was first characterized as an atypical member of the MAP kinase family with minimal basal kinase activity that can be potently activated by c‐Src and serum stimulation, positioning it as an integrator of extracellular signals."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nFurther studies have revealed that MAPK15 forms critical interactions with nuclear regulatory proteins. It binds to factors such as Hic-5 and responds to oncogenic signals—for instance, RET/PTC3 activates MAPK15 through a c-Abl–dependent mechanism—thereby modulating the transcriptional programs governed by nuclear receptors. In these contexts, MAPK15 negatively regulates transcription by inducing cytoplasmic translocation of receptors including the androgen receptor, glucocorticoid receptor, and ERRα, which suggests a broader function as a nuclear receptor corepressor."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "2", "end_ref": "5"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond its role in transcriptional regulation, MAPK15 is intimately involved in maintaining cellular homeostasis. It localizes to autophagic compartments by interacting with ATG8 family proteins through a conserved LC3-interacting region, thereby stimulating autophagosome formation and promoting SQSTM1 degradation in a kinase-dependent manner in response to serum and amino acid starvation. Simultaneously, MAPK15 associates with chromatin, where it protects genome integrity by stabilizing PCNA levels against HDM2-mediated degradation. In certain tumor contexts such as in aggressive germ cell tumors, overexpressed MAPK15 supports cell cycle progression by limiting p53 activation and by managing basal DNA damage through its regulatory effects on autophagy."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "6", "end_ref": "8"}]}, {"type": "t", "text": ""}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nCollectively, the current body of work underscores the multifunctional nature of MAPK15, implicating it in diverse cellular processes from signal transduction and transcriptional modulation to autophagy and genetic stability. This multifaceted kinase appears to play a context-dependent role in tumorigenesis, with its activity potentially tipping the balance between oncogenic transformation and genome preservation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": ""}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Mark K Abe, Matthew P Saelzler, Rafael Espinosa, et al. 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"}, {"type": "b", "children": [{"type": "t", "text": "Extracellular signal-regulated kinase 8 (ERK8) controls estrogen-related receptor α (ERRα) cellular localization and inhibits its transcriptional activity."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2011)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M110.179523"}], "href": "https://doi.org/10.1074/jbc.M110.179523"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "21190936"}], "href": "https://pubmed.ncbi.nlm.nih.gov/21190936"}]}, {"type": "r", "ref": 6, "children": [{"type": "t", "text": "Angela L Groehler, Deborah A Lannigan "}, {"type": "b", "children": [{"type": "t", "text": "A chromatin-bound kinase, ERK8, protects genomic integrity by inhibiting HDM2-mediated degradation of the DNA clamp PCNA."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Cell Biol (2010)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1083/jcb.201002124"}], "href": "https://doi.org/10.1083/jcb.201002124"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "20733054"}], "href": "https://pubmed.ncbi.nlm.nih.gov/20733054"}]}, {"type": "r", "ref": 7, "children": [{"type": "t", "text": "David Colecchia, Angela Strambi, Sveva Sanzone, et al. 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