p-Cresyl sulfate, a metabolite correlated with the development of bone abnormalities in chronic kidney disease (Tanaka et al., 2013), has been shown to contribute to the increase in intracellular production of reactive oxygen species and induced oxidative stress through the activation of JNK/p38 MAPK phosphorylation in osteoblastic cells. This evidence concerns the gene MAPK8 and chronic kidney disease.