Overexpressed zebrafish caspase-8 induces apoptosis in human HeLa cells.
(A-F) Control plasmid vector pME18S (A and B) or pME18S-Flag/zCasp8 carrying zebrafish casp8 cDNA (C and D) or pME18S-hCASP8 carrying human CASP8 cDNA (E and F) were transfected along with a reporter plasmid pJ7-LacZ into HeLa cells in the absence (A, C and E) or presence (B, D and F) of 100 μM z-VAD-fmk, a peptide caspase inhibitor. After 24 h, cells were fixed, stained with X-Gal and photographed under the microscope. Viable transfectants were observed as βGal-positive blue cells.