CASP8 and Miyoshi myopathy: To determine the role of the caspase-8 activation in Sp1 protein downregulation, we examined the effects of the caspase-8 inhibitor z-IETD-FMK on Sp1 protein levels in MM cells in the absence or presence of panobinostat at 0.05 μM and bortezomib at 5 nM in combination.