Related Experiment Video

Updated: Oct 24, 2026

Development of Inhibitors of Protein-protein Interactions through REPLACE: Application to the Design and Development Non-ATP Competitive CDK Inhibitors
10:33

Development of Inhibitors of Protein-protein Interactions through REPLACE: Application to the Design and Development Non-ATP Competitive CDK Inhibitors

Published on: October 26, 2015

Induced expression of p16(INK4a) inhibits both CDK4- and CDK2-associated kinase activity by reassortment of

B B McConnell1, F J Gregory, F J Stott

  • 1Imperial Cancer Research Fund Laboratories, London WC2A 3PX, United Kingdom.

Molecular and Cellular Biology
|February 18, 1999
PubMed

Insights

The p16(INK4a) tumor suppressor protein arrests the cell cycle by inhibiting cyclin-dependent kinases (CDKs). It sequesters CDK4, leading to p27(KIP1) inhibiting CDK2, thus halting cell proliferation.

Area of Science:

  • Molecular Biology
  • Cell Cycle Regulation
  • Cancer Research

Background:

  • p16(INK4a) is a crucial tumor suppressor protein involved in cell cycle control.
  • Its precise mechanism of action, particularly regarding CDK inhibition, requires further elucidation.

Purpose of the Study:

  • To investigate the detailed mechanism of action of the p16(INK4a) tumor suppressor protein.
  • To understand how p16(INK4a) influences cell cycle arrest by modulating CDK activity and complex formation.

Main Methods:

  • Utilized U2-OS cells with inducible p16(INK4a) expression.
  • Performed cell cycle analysis, kinase activity assays, and size fractionation of cellular lysates.

Main Results:

  • p16(INK4a) induction caused G1 cell cycle arrest by inhibiting retinoblastoma protein (pRb) phosphorylation via CDK4/CDK6.
  • p16(INK4a) also inhibited CDK2 activity through complex reassortment, with p27(KIP1) shifting from CDK4 to CDK2.
  • CDK4 sequestration by p16(INK4a) facilitated cyclin D1 association with CDK2.

Conclusions:

  • p16(INK4a) acts by sequestering CDK4, indirectly inhibiting CDK2 activity and causing cell cycle arrest.
  • This reassortment of cell cycle regulatory proteins, including p27(KIP1) and p21(CIP1), is critical for p16(INK4a)'s tumor suppressive function.

More Related Videos

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay12:26

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay

Published on: May 3, 2018

Related Concept Videos

Inhibition of Cdk Activity02:34

Inhibition of Cdk Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Inhibition of CDK Activity02:34

Inhibition of CDK Activity

The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
Positive Regulator Molecules02:39

Positive Regulator Molecules

Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.
M-Cdk Drives Transition Into Mitosis02:15

M-Cdk Drives Transition Into Mitosis

Checkpoints throughout the cell cycle serve as safeguards and gatekeepers, allowing the cell cycle to progress in favorable conditions and slow or halt it in problematic ones. This regulation is known as the cell cycle control system.
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
DNA Damage can Stall the Cell Cycle02:36

DNA Damage can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...
DNA Damage Can Stall the Cell Cycle02:36

DNA Damage Can Stall the Cell Cycle

In response to DNA damage, cells can pause the cell cycle to assess and repair the breaks. However, the cell must check the DNA at certain critical stages during the cell cycle. If the cell cycle pauses before DNA replication, the cells will contain twice the amount of DNA. On the other hand, if cells arrest after DNA replication but before mitosis, they will contain four times the normal amount of DNA. With a host of specialized proteins at their disposal,cells must use the right protein at...