SMPD1 and infection: Ad5H2E-PPE1(3x)-ASMase-mediated ASMase overexpression led to generation of physiologically-active enzyme, as ASMase activity increased 8.3-fold in homogenates of transduced BAEC from a baseline of 6.7±1.1 to 47.3±5.0 nmol/h (P<0.001) at 72 h post-infection (Fig.3A).