CASP3 and squamous cell carcinoma: Despite the importance of determining the type of cell death, in our preceding report we have detected that SN-38, an in vivo active antitumor metabolite of the antitumor drug irinotecan, could induce diverse types of cell death in two oral squamous cell carcinoma cell lines: (i) apoptosis mediated by caspase-3 activation as well as fragmentation of the internucleosomal DNA in HSC-2 cell type.