High ADAR1 mediates resistance of MM cells toward MM therapies. (A) Correlation of ADAR1 expression with patients’ response toward bortezomib-based and immunomodulatory drugs (IMIDs)-based treatments on the CoMMpass clinical trial. Poor response is represented by patients in stable disease and progressive disease stages. Good response is represented by patients who demonstrated complete response, very good partial response, and partial response. (B) Cell viability of U266-shCtrl and U266-shADAR1 cells on treatment with bortezomib of increasing concentration at 48 hours. (C) Western blot analysis of U266 on bortezomib treatment at different times (upper) and doses (lower). (D) Western blot analysis of the wild type (WT) and bortezomib-resistant (P100V) RPMI-8226 cell line. WT cell line was cultured in standard medium, whereas P100V was persistently cultured in medium containing 100 nM bortezomib. **P < .05; ***P < .001.