SPHK1 and breast cancer: Lei et al. (8) used data mining and the Kaplan-Meier plotter (http://kmplot.com/analysis/index.php?p=service&cancer=breast) to establish relationships between messenger RNA levels (rather than protein) of SphK1, SphK2, sphingosine 1-phosphate receptor 1 (S1P1), or sphingosine 1-phosphate receptor 2 (S1P2) and 10 year relapse free survival of non-classified breast cancer (BCA) patients.