SGPP1 and lung cancer: To rule out the different levels of plasma S1P being related to its dephosphorylation by means of sphingosine-1-phosphate phosphatases (SGPP1 and SGPP2, enzymes that convert S1P into sphingosine), or its degradation by means of sphingosine-1-phosphate lyase (SGPL1, an enzyme that degrades S1P into hexadecenal and phosphoethanolamine), we evaluated these enzyme transcript levels in lung cancer tissues.