Follistatin (FST) 344 is a synthetic peptide sequence corresponding to a human follistatin isoform, widely used as a laboratory reagent to study ligand sequestration within the transforming growth factor-β (TGF-β) superfamily. In experimental systems, follistatin-derived reagents are used to modulate the extracellular availability of select ligands, including activins and myostatin, enabling mechanistic investigation of downstream signaling behavior under controlled conditions.

Follistatin transcripts and protein isoforms have been detected across multiple tissue contexts, supporting ongoing basic research into isoform-dependent expression patterns and pathway regulation.

Source: NCBI Gene

Source: Uniprot

Sequence: MVRARHQPGG LCLLLLLLCQ FMEDRSAQAG NCWLRQAKNG RCQVLYKTEL SKEECCSTGR LSTSWTEEDV NDNTLFKWMI FNGGAPNCIP CKETCENVDC GPGKKCRMNK KNKPRCVCAP DCSNITWKGP VCGLDGKTYR NECALLKARC KEQPELEVQY QGRCKKTCRD VFCPGSSTCV VDQTNNAYCV TCNRICPEPA SSEQYLCGND GVTYSSACHL RKATCLLGRS IGLAYEGKCI KAKSCEDIQC TGGKKCLWDF KVGRGRCSLC DELCPDSKSD EPVCASDNAT YASECAMKEA ACSSGVLLEV KHSGSCNSIS EDTEEEEEDE DQDYSFPISS ILEW
Molecular Weight: 3780 g/mol
PubChem CID: 178101631
Synonyms: Activin-Binding Protein, FST

• Mechanistic studies of activin neutralization and activin receptor signaling modulation
• Experimental interrogation of myostatin/activin pathway crosstalk within TGF-β superfamily networks
• Cell-based assays evaluating SMAD pathway activation, transcriptional responses, and ligand competition dynamics
• Preclinical model investigations of pathway-regulated tissue remodeling, fibrosis markers, and inflammatory signaling endpoints
• Comparative analyses across follistatin isoforms and engineered variants in controlled laboratory settings

Follistatin-associated activity in research settings is generally attributed to high-affinity binding of extracellular ligands (notably activins), limiting ligand availability for receptor engagement and downstream signal propagation. This mechanism is commonly used to study changes in SMAD-dependent transcriptional programs and to map feedback behavior within activin–follistatin regulatory loops.

In addition to activin-related signaling, preclinical literature has investigated follistatin interactions with myostatin and the resulting effects on pathway readouts relevant to ligand sequestration, receptor occupancy, and downstream molecular markers in animal and cellular models^{[2], [3]}.

Ligand Sequestration Studies in Myostatin/Activin Signaling Models

Animal and cellular studies have used follistatin-based approaches (including protein, mRNA, and gene-expression systems) to evaluate the consequences of myostatin/activin pathway inhibition on molecular markers, tissue morphology, and functional readouts in controlled experimental designs^{[1], [3], [4], [5]}.

Strength-related readouts reported in follistatin-associated experimental paradigms.
Source: PubMed

Oncology Model Context (Expression and Mechanistic Associations)

Preclinical investigations and molecular profiling studies have examined follistatin expression in tumor-associated contexts and evaluated mechanistic associations with activin-related signaling, migration, and metastatic behavior in defined experimental systems, including mouse models^{[6], [7], [8], [9]}.

Recurrence-associated probability curves in breast cancer datasets stratified by follistatin (FST) expression.
Source: PubMed

Cell Proliferation, Fibrosis Markers, and Liver Model Systems

Mechanistic research in hepatocyte and hepatic stellate cell biology has examined the activin–follistatin axis in relation to proliferation-associated behavior, apoptosis markers, and fibrosis-related endpoints in controlled animal and cell-based models^{[10], [11], [12]}.

Developmental Biology and BMP/TGF-β Signaling Context

Developmental model studies have evaluated TGF-β and BMP signaling dynamics in processes such as optic fissure fusion, providing context for investigating how pathway antagonism and related modulators influence morphogenesis-associated signaling outcomes in model systems^[13].

Metabolic and Endocrine Pathway Investigations in Animal Models

Preclinical studies have evaluated forced expression of follistatin in defined animal model systems to assess pathway-regulated molecular and physiological endpoints, including pancreatic β-cell biology and glycemic measurements, under controlled experimental conditions^[15].

Note: Citations may include a mixture of preclinical reports and broader pathway reviews. Any cited clinical material is provided solely as bibliographic context and should not be interpreted as suggesting clinical, diagnostic, or therapeutic use.

• Supplied as a research-grade reagent intended for controlled laboratory workflows
• Identity and composition supported by analytical characterization (methodology may vary by lot)
• Not manufactured or labeled for diagnostic, therapeutic, clinical, or veterinary applications

1. C. Schumann et al., “Increasing lean muscle mass in mice via nanoparticle-mediated hepatic delivery of follistatin mRNA,” Theranostics, vol. 8, no. 19, pp. 5276–5288, Oct. 2018.
2. L. R. Rodino-Klapac, A. M. Haidet, J. Kota, C. Handy, B. K. Kaspar, and J. R. Mendell, “Inhibition of myostatin with emphasis on follistatin as a therapy for muscle disease,” Muscle Nerve, vol. 39, no. 3, pp. 283–296, Mar. 2009.
3. A. Iskenderian et al., “Myostatin and activin blockade by engineered follistatin results in hypertrophy and improves dystrophic pathology in mdx mouse more than myostatin blockade alone,” Skelet. Muscle, vol. 8, Oct. 2018.
4. A. M. Haidet et al., “Long-term enhancement of skeletal muscle mass and strength by single gene administration of myostatin inhibitors,” Proc. Natl. Acad. Sci. U. S. A., vol. 105, no. 11, pp. 4318–4322, Mar. 2008.
5. C. Barbé et al., “Role of IGF-I in follistatin-induced skeletal muscle hypertrophy,” Am. J. Physiol. – Endocrinol. Metab., vol. 309, no. 6, pp. E557–E567, Sep. 2015.
6. C. Zabkiewicz, J. Resaul, R. Hargest, W. G. Jiang, and L. Ye, “Increased Expression of Follistatin in Breast Cancer Reduces Invasiveness and Clinically Correlates with Better Survival,” Cancer Genomics Proteomics, vol. 14, no. 4, pp. 241–251, Aug. 2017.
7. D. D. Seachrist, S. T. Sizemore, E. Johnson, F. W. Abdul-Karim, K. L. Weber Bonk, and R. A. Keri, “Follistatin is a metastasis suppressor in a mouse model of HER2-positive breast cancer,” Breast Cancer Res. BCR, vol. 19, no. 1, p. 66, 05 2017.
8. E. Bloise et al., “Differential expression of follistatin and FLRG in human breast proliferative disorders,” BMC Cancer, vol. 9, p. 320, Sep. 2009.
9. L. SHI, J. RESAUL, S. OWEN, L. YE, and W. G. JIANG, “Clinical and Therapeutic Implications of Follistatin in Solid Tumours,” Cancer Genomics Proteomics, vol. 13, no. 6, pp. 425–436, Oct. 2016.
10. H. Ooe et al., “Proliferation of rat small hepatocytes requires follistatin expression,” J. Cell. Physiol., vol. 227, no. 6, pp. 2363–2370, Jun. 2012.
11. S. Patella, D. J. Phillips, J. Tchongue, D. M. de Kretser, and W. Sievert, “Follistatin attenuates early liver fibrosis: effects on hepatic stellate cell activation and hepatocyte apoptosis,” Am. J. Physiol. Gastrointest. Liver Physiol., vol. 290, no. 1, pp. G137-144, Jan. 2006.
12. M. Grusch et al., “Deregulation of the activin/follistatin system in hepatocarcinogenesis,” J. Hepatol., vol. 45, no. 5, pp. 673–680, Nov. 2006.
13. M. D. Knickmeyer et al., “TGFβ-facilitated optic fissure fusion and the role of bone morphogenetic protein antagonism,” Open Biol., vol. 8, no. 3, 2018.
14. M. P. Zimber et al., “Hair regrowth following a Wnt- and follistatin containing treatment: safety and efficacy in a first-in-man phase 1 clinical trial,” J. Drugs Dermatol. JDD, vol. 10, no. 11, pp. 1308–1312, Nov. 2011.
15. C. Zhao et al., “Overcoming Insulin Insufficiency by Forced Follistatin Expression in β-cells of db/db Mice,” Mol. Ther., vol. 23, no. 5, pp. 866–874, May 2015.

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