RARγ plays an important role in ATRA sensitizing MM cells to Cfz treatment. (A) Gene-profiling data from Zhan et al’s patient database were analyzed. Dot plot showing ATRA receptors (RARs and RXRs) expression (median-centered intensity) in plasma cells from healthy donors (n = 22), Monoclonal gammopathy of undetermined significance (MGUS; n = 44) and MM (n = 12). (B) Western blot showing expression of ATRA receptors (RARs and RXRs) in human MM cell lines. (C) Summarized results of flow cytometry data showing the apoptosis of MM.1S, ARP-1, or MM.1R MM cells with indicated treatment (10 µM RARα agonist AM80, RARβ agonist CD2314, RARγ agonist BMS961, or pan-RXR agonist SR11237) for 24 hours. (D) Western blot showing RARγ expression in Ctrl-KD or RARγ-KD MM cell lines. (E) Summarized results showing apoptosis of Ctrl-KD or RARγ-KD MM cells pulsed with 1-hour Cfz treatment followed by ATRA treatment for 24 hours. Student t test was used to compare 2 samples. n.s., no significance. *P < .05; **P < .01.