MLN9708 leads to an increase of ubiquitinated proteins in MM cell lines (MM.1S); an increase in cleavage of poly(ADP)ribose polymerase (PARP), a marker of apoptosis; an activation of caspase-3, -8 and -9; upregulation of signaling pathways such as p53-p21, p53-NOXA-PUMA and Rb-E2F; activation of ER stress response proteins and inhibition of NF-κB pathway [101]. Here, RB1 is linked to Miyoshi myopathy.