Syk抑制剂II，一种细胞可渗透的嘧啶-羧酰胺化合物，可作为Syk的有效，选择性和ATP竞争性抑制剂（IC50 = 41 nM），而仅在以下时间影响PKCe，PKCbII，ZAP-70，Btk和Itk更高的浓度（IC50分别为5.1、11、11.2、15.5和22.6μM）。体外抑制Rce-2H3细胞中FceRI介导的5-HT释放（IC50 = 460 nM）和体内小鼠抑制被动皮肤过敏反应（PCA）（ID50 = 13.2 mg / kg，sc）。 Syk Inhibitor II, a cell-permeable pyrimidine-carboxamide compound that acts as a potent, selective, and ATP-competitive inhibitor of Syk (IC50 = 41 nM), while affecting PKCe, PKCbII, ZAP-70, Btk, and Itk only at much higher concentrations (IC50 = 5.1, 11, 11.2, 15.5, and 22.6μM, respectively). Inhibits FceRI-mediated 5-HT release in RBL-2H3 cells in vitro (IC50 = 460 nM) and passive cutaneous anaphylaxis (PCA) reaction in mice in vivo (ID50 = 13.2 mg/kg, s.c.).