CASP6 and retinal ischemia: Similar experiments were carried out to evaluate whether CASP3 or CASP6 activation was dependent on CASP8: at 2 days after cerebral ischemia or 14 days after retinal ischemia, there was a significant reduction in the levels of CASP3 and CASP6 cleavage products in Z-IETD-FMK-treated rats (P<0.001; Figures 5c, f, and g).