CASP3 and infection: Similarly, our study also demonstrates that knockdown of SPHK2 significantly reduced the level of caspase 3 activity in DENV-infected Huh7 cells and the reduction in caspase 3 activity was correlated with the increasing of viable cells in the SPHK2 inhibitor-treated DENV-infected Huh7 cells at 48 and 72 hours post infection (S3 Fig).