{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n E2F‐associated phosphoprotein (EAPP) is a nuclear regulatory protein that interacts with the activating members of the E2F transcription factor family to modulate transcription of cell‐cycle and stress‐responsive genes. Elevated levels of EAPP are frequently observed in transformed cells, where it both enhances transcription from several cell‐cycle–regulated promoters and modulates cellular proliferation. In particular, EAPP has been shown to stimulate the MDR1 promoter—thereby increasing P‐glycoprotein expression and potentially contributing to multidrug resistance in tumor cells."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": " Concurrently, analyses in human cell lines have demonstrated that EAPP overexpression increases the S‐phase cell fraction via E2F‐dependent transcriptional modulation, whereas its knockdown reduces S‐phase entry; these findings indicate that an optimal EAPP level is critical for balancing proliferation and cell‐cycle arrest."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "2", "end_ref": "4"}]}, {"type": "t", "text": " Moreover, EAPP is essential for full transcriptional activation of the p21 gene, and its overexpression can confer resistance to DNA damage–induced apoptosis in a p21‐dependent manner, whereas insufficient levels of EAPP lead to reduced expression of p21 and other genes, ultimately causing apoptosis."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In addition to these cell‐cycle effects, EAPP functions as a transcriptional repressor in certain contexts. It competes with Sp1 for binding at the monoamine oxidase B (MAO B) gene core promoter, thereby down‐regulating MAO B expression and modulating glucocorticoid responses and stress signaling. This repressive activity, along with observed alterations in the expression of other stress‐responsive genes such as Mmp9, Npy, and Nosip following EAPP knockdown, implicates EAPP in the orchestration of cellular stress responses."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, deletion mapping studies that include the EAPP locus have raised the possibility of its involvement in developmental disorders—such as holoprosencephaly‐like phenotypes—although its precise contribution to developmental anomalies remains to be fully established."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Collectively, these findings indicate that EAPP is a multifunctional transcriptional modulator whose dosage‐sensitive activities regulate cell proliferation, apoptosis, drug resistance, and stress response. Such diverse roles underscore its potential impact on tumorigenesis and, possibly, on human developmental disorders.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Peter Andorfer, Hans Rotheneder "}, {"type": "b", "children": [{"type": "t", "text": "Regulation of the MDR1 promoter by E2F1 and EAPP."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "FEBS Lett (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.febslet.2013.03.026"}], "href": "https://doi.org/10.1016/j.febslet.2013.03.026"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23542036"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23542036"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Michael Novy, Regina Pohn, Peter Andorfer, et al. 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