INS and diabetic kidney disease: Additionally, SPHK1 protein expression and S1P levels are increased in podocytes of DKD patients compared to healthy individuals [49,50] and SPHK1 protein expression was shown to be increased in a streptozotocin (STZ)-induced mouse model of DKD [49,51] and in glomeruli of mice with Alloxan (a toxic glucose analogue that destroys insulin producing cells in the pancreas) induced diabetes in association with S1P accumulation [50].