CASP8 and Miyoshi myopathy: Addition of z-IETD-FMK antagonized the Sp1 reduction by the combination of panobinostat and bortezomib and maintained high Sp1 protein levels in MM cells (Figure 3E), confirming the predominant role of caspase-8 activation in synergistic downregulation of Sp1 protein by panobinostat plus bortezomib.