Catalog No. size PriceQuantity
M60432-2S 2mg solid $89
M60432-10S 10mg solid $356


S3I-201, also known as NSC 74859, is a cell-permeable Stat3 inhibitor that binds to the Stat3-SH2 domain, prevents Stat3 phosphorylation/activation, dimerization, and DNA-binding.

Product information

CAS Number: 501919-59-1

Molecular Weight: 365.36

Formula: C16H15NO7S



Chemical Name: 2-hydroxy-4-(2-(tosyloxy)acetamido)benzoic acid

Smiles: CC1C=CC(=CC=1)S(=O)(=O)OCC(=O)NC1=CC(O)=C(C=C1)C(O)=O


InChi: InChI=1S/C16H15NO7S/c1-10-2-5-12(6-3-10)25(22,23)24-9-15(19)17-11-4-7-13(16(20)21)14(18)8-11/h2-8,18H,9H2,1H3,(H,17,19)(H,20,21)

Technical Data

Appearance: Solid Power.

Purity: ≥98% (or refer to the Certificate of Analysis)

Solubility: DMSO: 25 mg/mL

Shipping Condition: Shipped under ambient temperature as non-hazardous chemical or refer to Certificate of Analysis

Storage Condition: Dry, dark and -20 oC for 1 year or refer to the Certificate of Analysis.

Shelf Life: ≥12 months if stored properly.

Stock Solution Storage: 0 - 4 oC for 1 month or refer to the Certificate of Analysis.

Drug Formulation: To be determined.

HS Tariff Code: 382200

How to use

In Vitro:

S3I-201 (NSC-74859) preferentially inhibits Stat3 DNA-binding activity over that of Stat1 (IC50 values, Stat3•Stat3, 86±33 μM; Stat1•Stat3, 160±43 μM; and Stat1•Stat1, >300 μM) and inhibits that of Stat5 with IC50 of 166±17 μM). S3I-201 significantly reduces viable cell numbers and inhibits growth of transformed mouse fibroblasts NIH 3T3/v-Src and breast carcinoma cell lines (MDA-MB-231, MDA-MB-435, and MDA-MB-468). At 30-100 μM, S3I-201 induces significant apoptosis in the representative human breast carcinoma cell line MDA-MB-435 and NIH 3T3/v-Src, both of which harbor constitutively active Stat3. The breast carcinoma MDA-MB-435 cell line is more sensitive to 30 μM S3I-201. By contrast, the human breast cancer MDA-MB-453 cells and the normal mouse fibroblasts (NIH 3T3), which do not contain abnormal Stat3 activity, are less sensitive to S3I-201 at 100 μM or less. At 300 μM or higher, S3I-201 induced general, nonspecific cytotoxicity independent of Stat3 activation status. Huh-7 cells do not express β2SP or TBGFR2 and are sensitive to STAT3 inhibition, with an IC50 of 100 μM for S3I-201, regardless of CD133+ status. The IC50 of S3I-201 is 150 μM for Huh-7 and SNU-398 cells, 15 μM for SNU-475 cells and 200 μM for SNU-182 cells. S3I-201 inhibits breast carcinoma MDA-MB-435, MDA-MB-453 and MDA-MB-231 cell lines with an IC50 close to 100 μM.

In Vivo:

Human breast (MDA-MB-231) tumor-bearing mice are given an i.v. injection of S3I-201 (NSC-74859) or vehicle every 2 or every 3 days for 2 weeks, and tumor measurements are taken every 2-3 days. Compared with control (vehicle-treated) tumors, which continued to grow, human breast tumors in mice that received S3I-201 display strong growth inhibition. Continued evaluation of treated mice on termination of treatment shows no resumption of tumor growth, suggesting potentially a long-lasting effect of S3I-201 on tumor growth. Compared with vehicle-treated control tumors (n=15), which continued to grow, S3I-201 treatment of somatotroph tumor xenografts (n=15) significantly attenuated tumor growth for the duration of the experiment. Tumors derived from S3I-201-treated rats are significantly smaller than those from the untreated group (220±16 mm3 vs. 287±16 mm3, P<0.01) as early as 5 days after S3I-201 injection. Fifteen days after treatments, the average tumor volume of S3I-201-treated rats is 64% of that of controls (449±40 mm3 vs. 708±83 mm3, P<0.01). Rats are sacrificed and tumors are harvested 15 days after treatment initiation. The average tumor weight of S3I-201-treated rats is 78±8 mg, while tumors derived from control rats weighed 114±13 mg (32% reduction; P<0.05).


  1. Siddiquee K, et al. Selective chemical probe inhibitor of Stat3, identified through structure-based virtual screening, induces antitumor activity. Proc Natl Acad Sci U S A. 2007 May 1;104(18):7391-6.
  2. Lin L, et al. The STAT3 inhibitor NSC 74859 is effective in hepatocellular cancers with disrupted TGF-β signaling. Oncogene. 2009 Feb 19;28(7):961-72.
  3. Zhou C, et al. STAT3 upregulation in pituitary somatotroph adenomas induces growth hormone hypersecretion. J Clin Invest. 2015 Apr;125(4):1692-702.

Products are for research use only. Not for human use.

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