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Updated: Aug 16, 2026

Impedance-based Real-time Measurement of Cancer Cell Migration and Invasion
Published on: April 2, 2020
Essential role of CIB1 in regulating PAK1 activation and cell migration
Tina M Leisner1, Mingjuan Liu, Zahara M Jaffer
1Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
Abstract:
p21-activated kinases (PAKs) regulate many cellular processes, including cytoskeletal rearrangement and cell migration. In this study, we report a direct and specific interaction of PAK1 with a 22-kD Ca2+-binding protein, CIB1, which results in PAK1 activation both in vitro and in vivo. CIB1 binds to PAK1 within discrete regions surrounding the inhibitory switch domain in a calcium-dependent manner, providing a potential mechanism of CIB1-induced PAK1 activation. CIB1 overexpression significantly decreases cell migration on fibronectin as a result of a PAK1-and LIM kinase-dependent increase in cofilin phosphorylation. Conversely, the RNA interference-mediated depletion of CIB1 increases cell migration and reduces normal adhesion-induced PAK1 activation and cofilin phosphorylation. Together, these results demonstrate that endogenous CIB1 is required for regulated adhesion-induced PAK1 activation and preferentially induces a PAK1-dependent pathway that can negatively regulate cell migration. These results point to CIB1 as a key regulator of PAK1 activation and signaling.
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