Study of de Wilt et al. showed there was obvious cross-resistance in some of the bortezomib resistant NSCLC cell lines harboring PSMB5 mutations to other proteasome inhibitors specifically targeting β-subunits (including MG132 which targets all β subunits of the proteasome, irreversible proteasome inhibitors, such as carfilzomib and an derivative ONX 0912). Here, PSMB5 is linked to non-small cell lung carcinoma.