Extracellular signals regulate actin dynamics through G protein-coupled receptors (GPCRs), integrins, and receptor tyrosine kinases (RTKs). GPCRs constitute a large protein family of receptors, that sense molecules outside the cell and activate inside signal transduction pathways and, ultimately, cellular responses. Integrins are transmembrane receptors that are the bridges for cell-cell and cell-extracellular matrix (ECM) interactions. When triggered, integrins in turn trigger chemical pathways to the interior (signal transduction), such as the chemical composition and mechanical status of the ECM, which results in a response (activation of transcription) such as regulation of the cell cycle, cell shape, and/or motility; or new receptors being added to the cell membrane. Receptor tyrosine kinase (RTK) is part of the larger family of protein tyrosine kinase. Receptor tyrosine kinase consists of EGFR, PDGFR, MCSFR, IGF1R, INSR, NGFR, FGFR, VEGFR and HGFR. Intracellular signals regulate of the cell's response to external cues occurs through Rho. Rho is a member of the Ras superfamily of small GTP-binding proteins that play a central role in diverse biological processes such as Actin cytoskeleton organization, Microtubule dynamics, Gene transcription, Oncogenic transformation, Cell cycle progression, Adhesion and Epithelial wound repair. GEF(guanine nucleotide exchange factors) is activator. ROCK and PAK are downstream protein kinase effectors. Aberrant control of cytoskeletal signaling, which can result in a disconnection between extracellular stimuli and cellular responses, is often seen in immune pathologies, developmental defects, and cancer.
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Thanks to Sino Biological for providing the pathways.