While tubular epithelial cells can undergo complete morphologic and functional transition into myofibroblasts in a TGF-β/JNK dependent mechanism in vitro (Fan et al., 1999; Mariasegaram et al., 2010), this transition is a rare event in vivo in human and experimental kidney disease (Ng et al., 1998; Jinde et al., 2001). Here, MAPK8 is linked to kidney disorder.