Sphk2–/– mice develop less renal fibrosis than Sphk1–/– mice (Figures 1B–E), and S1P and SphK2 are part of a corepressor complex that influences histone acetylation and gene expression (15, 26); therefore we focused on identifying targets downstream of SphK2. Here, SPHK1 is linked to renal fibrosis.