Moreover, Sphk1 is closely associated with CKD [27, 28] Consistent with these results and similar to increased Sphk1 expression in renal biopsy of patients with CKD (Supplementary Figure 5A), we found that Sphk1 was significantly up-regulated in the UUO-induced obstructed kidney in mice (Figure 6A and Supplementary Figure 5B). Here, SPHK1 is linked to chronic kidney disease.