Paracrine signaling via cytokine and growth factor release

Paracrine signaling via cytokine and growth factor release is not a molecule or receptor but a *biological signaling mechanism* wherein **cytokines** and **growth factors**, which are soluble protein messengers, are secreted by one cell and act on neighboring cells through binding to specific cell surface receptors. This mechanism is essential for regulating a wide array of biological processes including cell proliferation, differentiation, migration, survival, immune responses, tissue organization, and homeostasis[1][3][4][7]. The effect of paracrine signals is usually rapid and localized, as the released molecules are quickly degraded or taken up, restricting their action to cells in close proximity[2][3]. Cytokines and growth factors themselves are diverse families of proteins (e.g., interleukins, interferons, tumor necrosis factors, platelet-derived growth factors, transforming growth factor-betas, vascular endothelial growth factors) that can signal in autocrine, paracrine, or endocrine fashion, but **paracrine signaling** refers specifically to their action on adjacent cells[3][7]. In human disease, dysregulated paracrine cytokine/growth factor signaling contributes to cancer, inflammation, fibrosis, and other pathologies[6][4]. **This entry is not a valid molecular therapeutic target** (such as a single defined receptor, enzyme, transporter, or gene product), but rather describes a *mode of intercellular communication*. For structured data purposes, this should be flagged as “is_incorrect: true”; refer instead to specific cytokine or growth factor receptors or the individual molecules involved for therapeutic targeting.