SPHK1 and rheumatoid arthritis: Geniposide also significantly inhibited SphK1 activity, the S1P level, and the expression of SphK1 and S1PR1 in FLSs, indicating that geniposide reduced SphK1 activity by recovering the homeostasis of pro- and anti-angiogenic factors, thus disturbing SphK1-s1p-s1pr1 signaling transduction, eliminating synovial microangiogenesis and displaying anti-RA angiogenesis effect [87].