Intriguingly, promising results for synergistic therapy between proteasome inhibitor PS-341 and 153Sm-EDTMP were revealed by Goel et al. Apoptosis induction (pro-caspase-3 and PARP cleavage) was observed in highly resistant myeloma cell lines after 24 h of combined treatment, even though neoplastic cell viability was 68%46. Here, CASP3 is linked to plasma cell myeloma.