SPHK1 and serum lipopolysaccharide activity: To determine whether Sphk-1 represents a molecular mediator associated with the observed hyperinflammatory response in aging, Sphk-1 mRNA expression was examined by quantitative PCR in hepatic tissues of young and aged rats subjected to endotoxemia, and its expression was found to correlate with CD14, a known component of the LPS receptor and the TLR signaling pathways.