Table III.

The effect of photodynamic therapy (PDT) on global sphingolipids in siControl- and siDES-transfected cells.

Cell type	Pc 4 (nM) for PDT	Global ceramides p-Value	Fold-change†	Global dihydroceramides p-Value	Fold-change†
siControl	250	0.01	1.78	0.00001	12.51
	500	0.01	2.21	0.0001	10.10
siDES	250	0.11	1.73	0.01	4.01
	500	0.00005	3.92*	0.00004	5.68

^†Post-PDT relative to that in untreated controls.

^*The increase in global ceramides after PDT was higher in siDES- than in siControl-transfected cells (p<0.011). DES, Dihydroceramide desaturase 1.