Fluorescently labeled d-erythro-sphingosines have been successfully synthesized in 9 and 12 steps starting from commercially available Garner aldehyde. Determining the influence of the nature, position and linkage of the label on the in vitro phosphorylation rate by sphingosine kinases 1 and 2 resulted in the identification of a pyrene-and a NBD-labeled sphingosine which are both phosphorylated with efficiency comparable to the natural ...