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Updated: Jun 14, 2026

Studying TGF-β Signaling and TGF-β-induced Epithelial-to-mesenchymal Transition in Breast Cancer and Normal Cells
Published on: October 27, 2020
Rac1 modulates TGF-beta1-mediated epithelial cell plasticity and MMP9 production in transformed keratinocytes
Juan F Santibáñez1, Jelena Kocić, Angels Fabra
1Laboratorio de Biología Celular, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile. jfsantibanez@imi.bg.ac.rs
Abstract:
Transforming growth factor-beta1 (TGF-beta1) activates Rac1 GTPase in mouse transformed keratinocytes. Expression of a constitutively active Q61LRac1 mutant induced an epithelial to mesenchymal transition (EMT) linked to stimulation of cell migration and invasion. On the contrary, expression of a dominant-negative N17TRac1 abolished TGF-beta1-induced cell scattering, migration and invasion. Moreover, Q61LRac1 enhanced metalloproteinase-9 (MMP9) production to levels comparable to those induced by TGF-beta1, while N17TRac1 was inhibitory. TGF-beta1-mediated EMT involves the expression of the E-cadherin repressor Snail1, regulated by the Rac1 and mitogen-activated protein kinase (MAPK) pathways. Furthermore, MMP9 production was MAPK-dependent, as the MEK inhibitor PD98059 decreased TGF-beta1-induced MMP9 expression and secretion in Q61LRac1 expressing cells. We propose that regulation of TGF-beta1-mediated plasticity of transformed keratinocytes requires the cooperation between the Rac1 and MAPK signalling pathways.
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