RepSox (HCl), 5 mg

From STEMCELL Technologies, RepSox Hydrochloride is a cell-permeable, selective inhibitor of the TGF-β type 1 receptor (TGFβRI) ALK5, classified as an Activin/BMP/TGF-β pathway inhibitor. It is supplied as the hydrochloride salt of the molecule, with alternative names Alk 5 Inhibitor II, E 616452, and SJN 2511, and chemical name 2-[3-(6-methyl-2-pyridinyl)-1H-pyrazol-4-yl]-1,5-naphthyridine, monohydrochloride.

Reported IC₅₀ values are 4 nM for ALK5 autophosphorylation, 18 nM for the TGF-β cellular assay, and 23 nM for ALK5 binding in HepG2 cells (Gellibert et al.). The compound shows less potent activity (IC₅₀ > 16 µM) against 9 related kinases, including p38 MAPK and GSK3. The CAS Number is 2319939-07-4, chemical formula C₁₇H₁₃N₅ · HCl, molecular weight 323.8 g/mol, and purity ≥ 98%. It appears as a crystalline solid.

The product is stable for 12 months from date of receipt when kept at -20°C as supplied and protected from prolonged exposure to light. Solubility is reported as ≤ 1.5 mM in absolute ethanol and ≤ 610 μM in PBS (pH 7.2). Published applications include enhancing reprogramming of mouse embryonic fibroblasts transduced with OCT4, KLF4, and c-MYC; direct lineage reprogramming of fibroblasts to mature neurons in combination with CHIR99021, Valproic Acid, Forskolin, SP600125, Gö6983, and Y-27632; replacing SOX2 in reprogramming of mouse fibroblasts to induced pluripotent stem cells; and inducing differentiation of human pancreatic progenitor cells into insulin-producing cells, alone or in combination with Forskolin, Dexamethasone, and Nicotinamide.