2-5A-RNase L activation mediates MM cell apoptosis in response to ATRA+Cfz. (A) RNA gel electrophoresis and (B) summarized results showing RNA integrity number (RIN) of ARP-1 (left panel) or MM.1S (right panel) cells with indicated treatment for 16 hours. The positions of 18S and 28S ribosomal RNA are indicated. (C) Summarized data of fluorescent confocal images showing expression of dsRNA, labeled by anti-dsRNA J2 antibody, in ARP-1 or MM.1S cells with indicated treatment for 8 hours. (D) Box plot showing the average level of A-to-I editing in MM cells from 6 CoMMpass patients before (red dots) or after (blue dots) PI-based therapy (the detailed clinical information is listed in supplemental Table 5) by analyzing global editing sites across the whole transcriptome in the RNA-seq data. (E) Summarized results displaying apoptosis of MM.1S or ARP-1 MM cells transfected with or without 2-5A for 24 hours. 3-5A served as a negative control. (F) Summarized flow data showing apoptosis of ARP-1 (left panel) or MM.1S (right panel) cells treated with Cfz or ATRA+Cfz in the presence or absence of 20 µM curcumin for 24 hours. For panel A, representative result of at least 3 independent experiments is shown. Student t test was used to compare 2 samples. *P < .05; **P < .01; ***P < .001.