Whereas 1,25-OH-D production was clearly demonstrated in control arterial explants (7-fold, p<0.05, Fig 1D) and suggests 1α-OHase activity, 1,25-OH-D production in CKD explants was markedly reduced compared to control arteries, suggesting a reduction in 1α-OHase or increased 24-OHase enzyme activity (p<0.01). The gene discussed is CYP24A1; the disease is chronic kidney disease.