Halofuginone (RU-19110), the competitive inhibitor of prolyl-tRNA synthetase(Ki=18.3 nM), could also down-regulate Smad3 and blocked TGF-β signaling at 10 ng/ml in the mammal.

Prolyl-tRNA synthetase:18.3nM(Ki)

在哺乳动物中，halofuginone以10 ng/ml的浓度下调Smad3，阻断TGF-β信号传导，进而阻止纤维细胞向肌成纤维细胞的分化以及上皮细胞向间充质细胞的转变[2]。

Halofuginone明显延长了寄生虫感染小鼠的存活时间。通过口服0.2及1 mg/kg剂量的halofuginone，对感染的小鼠有显著的治愈效果。同样，注射0.2mg/kg的halofuginone也能延长感染小鼠的存活时间，但未能彻底治愈。在5 mg/kg剂量组的小鼠在治疗完成前死亡，无论是口服还是皮下注射。与口服相比，皮下注射halofuginone对小鼠的毒性似乎更大[3]。

Assay of ProRS activity: The prolyl tRNA synthetase domain of human EPRS (ProRS) is expressed in E.coli with a 6-his tag and purified. Enzymatic activity is assayed using incorporation of 3H Pro into the tRNA fraction essentially, except that the charged tRNA fraction is isolated by rapid batchwise binding to Mono Q sepharose and quantitated by liquid scintillation counting. For all kinetic assays, the concentration of active enzyme in the reaction is 40 nM. Similar inhibition by HF is seen using the human ProRS domain purified from bacteria and full length EPRS purified from rat liver.

Primary murine CD4+ CD25− T cells are activated through the TCR in Th17 polarizing conditions in the presence of either 10 nM MAZ1310 or HF and amino acid supplements. Th17 differentiation is assayed in the absence or presence of HF or borrelidin, with or without 1 mM threonine or proline supplementation. MEFs are treated with or without HF (50 nM) and/or Proline (2 mM) for 4 hours (CHOP, S100A4) or 24 hours (ColIA1, Col1A2).  (Only for Reference)