However, the upregulation of the same miR-21 and the resulting renal dysfunction in ccRCC could also be ascribable to the activation of a different molecular axis, involving the uremic toxin p-Cresyl sulfate, which fosters a hypoxic microenvironment trough HIF-1α [120]. The gene discussed is HIF1A; the disease is nonpapillary renal cell carcinoma.