Using this assay system, we demonstrated that the cytotoxic effect of proteasome inhibitors in MM cells was suppressed in the presence of stromal cells via repression of NOXA and ATF3, ER stress-related transcription factors (Figs 1 and 4A), which appear to represent BMSC-mediated drug resistance [11, 12]. The gene discussed is PMAIP1; the disease is Miyoshi myopathy.