PIWIL1 and plasma cell myeloma: PIWIL1 downregulation inhibited myeloma growth in xenograft models, and restraining the PIWIL1-regulated signaling pathway sensitized MM to the chemotherapeutic agents bortezomib, doxorubicin, and dexamethasone in vitro and in vivo, indicating that PIWIL1 is a potential therapeutic target for MM patients.