miR-21 is broadly upregulated in AKI and plays context-dependent roles: in septic AKI, miR-21-5p is induced in plasma and kidney tissue and appears to mitigate injury by targeting the pro-apoptotic gene RUNX1, as evidenced by improved renal function and reduced inflammation when miR-21-5p is overexpressed or delivered via endothelial progenitor cell exosomes; indeed, exosomal miR-21 therapy lowered tubular injury in septic AKI models [71]. The gene discussed is RUNX1; the disease is acute kidney injury.