Sphingosine-1-phosphate (S1P) is an endogenous signaling sphingolipid produced from metabolism of ceramides. S1P binds the S1P receptor and may inhibit HDACs. S1P exhibits neuroprotective activity as well as both pro-inflammatory and anti-inflammatory properties, depending on the model. S1P increases neuron viability and upregulates expression of Bcl-2 and Bcl-xl, inhibiting glucose deprivation stress. S1P upregulates expression of PAR4, promoting cell migration and COX-2 expression in vitro. Clinically, S1P preserves fertility and gonadal function in subjects exposed to cytotoxic agents such as chemotherapeutic compounds.