Cell signaling and signal transduction coordinate cellular communication
and the execution of diverse biological functions. This review synthesizes how cells
sense and integrate external and internal cues through core pathways, with emphasis on
G Protein–Coupled Receptor (GPCR) and Mitogen-Activated Protein Kinase (MAPK)
cascades that govern growth, differentiation, and apoptosis. We outline the roles of
second messengers, protein kinases, and transcription factors in propagating and tuning
signals, and describe regulatory mechanisms that maintain fidelity and specificity. We
also summarize how pathway dysregulation underlies disease, including cancer, and
discuss the therapeutic implications of targeting signaling networks.
Keywords: Cell signaling, Signal transduction, GPCR, MAPK, Second messengers, Protein kinases, Transcription factors, Apoptosis.
