EPO and chronic kidney disease: This regulation of HIF-2α by Sphks may also have therapeutic utility as it proposes that Sphk2 inhibitors could have beneficial effects in patients suffering from chronic kidney disease and anemia, while Sphk1 inhibitors could be useful to treat diseases where erythropoietin synthesis is too high, such as secondary congenital erythrocytosis, that develops due to mutations in genes regulating Epo syntheses, such as VHL, EGLN1, EPAS1, or EPO [68].