Transforming Growth Factor Beta 1 (TGF-β1) is an endogenous cytokine produced by various cell types, including platelets, macrophages, and fibroblasts. It belongs to the transforming growth factor beta superfamily, which is a group of proteins involved in cellular processes such as proliferation, differentiation, and apoptosis. TGF-β1 is synthesized as a precursor protein that undergoes proteolytic cleavage to become active. Researchers have extensively studied TGF-β1 due to its significant role in cellular regulation and its potential therapeutic applications. TGF-β1 plays a crucial role in regulating immune responses, wound healing, and maintaining tissue homeostasis. It is involved in the suppression of immune system activity, promoting the differentiation of regulatory T cells, and inhibiting the proliferation of T cells and natural killer cells. Additionally, TGF-β1 is a key factor in fibrosis and is implicated in the pathogenesis of various fibrotic diseases. Researchers have also explored its role in cancer biology, as it can both suppress and promote tumor growth depending on the context. TGF-β1 exerts its effects by binding to a specific receptor complex on the cell surface, which includes TGF-β receptors type I and II. Upon ligand binding, these receptors activate intracellular SMAD proteins, which translocate to the nucleus and regulate the expression of target genes. This signaling cascade is crucial for mediating the diverse biological effects of TGF-β1. The pharmacokinetic properties of TGF-β1 are not well-characterized, with limited data available on its half-life and metabolism. As an endogenous protein, its bioavailability and clearance are influenced by complex physiological processes. Clinically, TGF-β1 is not directly used as a therapeutic agent due to its pleiotropic effects and potential for adverse outcomes. However, researchers are investigating its modulation as a therapeutic strategy in conditions such as fibrosis and cancer. Regulatory agencies have not approved TGF-β1 as a drug, and its use is primarily confined to research settings.