SPHK1 and arthritic joint disease: Functional enrichment further supported that the primed genes are heavily involved in inflammatory response, arthritis-promoting functions (Ccl2, Cxcl5, Sphk1) and, interestingly, Wnt pathway (Bmp2, Rspo3, Cd44) and stem cell differentiation (Sox5, Nrp2, Cdk6) (Additional file 1: Fig. S12D).