Apoptosis induces expression of sphingosine kinase 1 to release sphingosine-1-phosphate as a "come-and-get-me" signal. - Gude DR; Alvarez SE; Paugh SW; Mitra P; Yu J; Griffiths R; Barbour SE; Milstien S; Spiegel S (FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2008)