To determine whether the activated caspases are involved in the apoptotic action of HF, we examined the effects of the broad-spectrum caspase inhibitor Z-VAD-fmk and selective inhibitors of caspase-3 (Z-DEVD-fmk), caspase-8 (Z-IETD-fmk) and caspase-9 (Ac-LEHD-CHO) on cell apoptosis as determined by annexin-V-FITC binding. The gene discussed is CASP8; the disease is hydrops fetalis.