MAPK8 and Friedreich ataxia: To investigate the functional role of Smad3 and/or JNK signaling pathways in the pathogenesis of FA-induced renal tubulointerstitial fibrosis and inflammation, a Smad3-specific inhibitor (SIS3) and/or a JNK inhibitor (SP600125) were administered daily to mice, beginning on day 6 days after FA injection.