R112 is an inhibitor of spleen tyrosine kinase (Syk; IC50 = 226 nM in cultured human mast cells) that acts in an ATP-competitive and reversible manner (Ki = 96 nM).1 It inhibits mast cell and basophil degranulation induced by anti-IgE cross-linking (EC50s = 353 and 280 nM, respectively). It also inhibits basophil degranulation induced by an allergen with an EC50 value of 490 nM. R112 inhibits the production of leukotriene C4 and decreases cytokine levels in cultured human mast cells.
1.Rossi, A.B., Herlaar, E., Braselmann, S., et al.Identification of the Syk kinase inhibitor R112 by a human mast cell screenJ. Allergy Clin. Immunol.118(3)749-755(2006)