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Related Concept Videos

Loss of Tumor Suppressor Gene Functions01:12

Loss of Tumor Suppressor Gene Functions

Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
Loss of Tumor Suppressor Gene Functions01:12

Loss of Tumor Suppressor Gene Functions

Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
Cancer-Critical Genes II: Tumor Suppressor Genes01:05

Cancer-Critical Genes II: Tumor Suppressor Genes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
Cancer-Critical Genes II: Tumor Suppressor Genes01:05

Cancer-Critical Genes II: Tumor Suppressor Genes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
Cancer-Critical Genes I: Proto-oncogenes01:33

Cancer-Critical Genes I: Proto-oncogenes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...

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Related Experiment Video

Updated: May 15, 2026

Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog
08:37

Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog

Published on: November 5, 2014

STOP gene Phactr4 is a tumor suppressor.

Nicole L Solimini1, Anthony C Liang, Chunxiao Xu

  • 1Department of Genetics, Harvard University Medical School, Boston, MA 02115, USA.

Proceedings of the National Academy of Sciences of the United States of America
|January 16, 2013
PubMed
Summary

Phosphatase and actin regulator 4 (PHACTR4) restrains cell proliferation and acts as a tumor suppressor. PHACTR4 is frequently deleted or mutated in various cancers, highlighting its role in preventing tumor development.

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Induction and Diagnosis of Tumors in Drosophila Imaginal Disc Epithelia
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Published on: November 5, 2014

Defining Gene Functions in Tumorigenesis by Ex vivo Ablation of Floxed Alleles in Malignant Peripheral Nerve Sheath Tumor Cells
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Area of Science:

  • Molecular biology
  • Cancer research
  • Genetics

Background:

  • Cancer arises from genetic and epigenetic changes enabling uncontrolled cell growth and survival.
  • A prior RNAi screen identified hundreds of suppressors of tumorigenesis and/or proliferation (STOP) genes.
  • The STOP gene set was enriched for known and putative tumor suppressor genes.

Purpose of the Study:

  • To investigate the tumor-suppressive role of the STOP gene, phosphatase and actin regulator 4 (PHACTR4).
  • To explore the mechanism by which PHACTR4 restrains cell proliferation and transformation.

Main Methods:

  • Conducted genetic RNAi screening to identify STOP genes.
  • Utilized shRNAs to deplete Phactr4 and assess its impact on cell proliferation and soft agar colony formation.
  • Examined Phactr4's role in an Rb-dependent pathway.
  • Analyzed tumor copy number and sequencing data for PHACTR4 alterations.
  • Complemented Phactr4-depleted cancer cell lines to evaluate tumor suppressor activity.

Main Results:

  • Depletion of Phactr4 increased cell proliferation and soft agar colony formation.
  • Phactr4 depletion maintained Rb phosphorylation upon growth factor withdrawal, indicating partial Rb-dependent function.
  • PHACTR4 was found to be significantly deleted and mutated across multiple tumor subtypes.
  • Restoring Phactr4 expression in cancer cell lines reduced proliferation, transformation, and tumor formation.

Conclusions:

  • PHACTR4 functions as a tumor suppressor by restraining normal cell proliferation.
  • PHACTR4 is frequently altered (deleted or mutated) in various human cancers.
  • Phactr4's tumor-suppressive activity is partly mediated through an Rb-dependent pathway.