Effect of short-chain exogenous ceramide on endogenous ceramide species profile in the (a) lung after C12Cer (1mg/kg, 24h, black) or vehicle (gray) and in (b) bovine pulmonary artery endothelial cells (thin layer chromatography of intra-cellular ceramides detected by DAG kinase assay) after C8Cer (10 μM; n=2). (c) Effect of C12Cer on the ASMase activity in the mouse lung (24h, mean +SD, *p =0.02). Effect of neutralizing ceramide-specific antibody (4mg/kg/d) on (d) lung ceramide species (mean +SE; *p =0.002) and on (e) lung apoptosis detected by active caspase-3 (arrows, bar 50 μm) induced by VEGFR-inh (3d).