Related Experiment Video
Updated: Aug 6, 2026

In Vitro Cultivation Techniques for Modeling Liver Organogenesis, Building Assembloids, and Designing Synthetic Tissues using Human Cell Lines
Published on: April 18, 2025
Integrin beta(1A) upregulates p27 protein amount at the post-translational level in human hepatocellular carcinoma
Yi Fu1, Li-Ying Wang, Yu-Long Liang
1Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Abstract:
Integrins mediate many fundamental cellular processes by binding to components of the extracellular matrix. We showed previously that integrin beta(1A) could inhibit cell proliferation. Integrin beta(1A) stimulated the promoter activity of p21(cip1) and enhanced its transcription in SMMC-7721 cells. In this study, we demonstrated that integrin beta(1A) upregulated p27(kip1) at the post-translational level in SMMC-7721 cells. Our results showed that integrin beta(1A) increased the p27 protein amount, both in cytoplasm and nucleus, but did not affect the p27 mRNA amount. Cycloheximide treatment experiment revealed that the half-life of p27 protein was prolonged in integrin beta1A overexpressing cells, indicating that integrin beta(1A) inhibited the degradation of p27 protein. Our data also provided evidence that both the proteasome and calpain were involved in the degradation of p27 protein in SMMC-7721 cells. Integrin beta(1A) decreased the Skp2 expression and repressed the activity of calpain during G1 phase in SMMC-7721 cells. Taken together, these results indicated that integrin beta(1A) might upregulate the protein amount of p27 through repressing Skp2-dependent proteasome degradation and calpain-mediated proteolysis in SMMC-7721 cells.
Related Concept Videos
Intracellular Signaling Affects Focal Adhesions
Some...
TGF - β Signaling Pathway
Activation of Integrins
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
Abnormal Proliferation
Interactions Between Signaling Pathways
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
Integrins
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...

