Fig. 1. PI resistance is reversible in multiple myeloma (MM).

a Flow cytometric detection of BCMA expression in a bone marrow sample derived from a relapsed MM patient. b BCMA⁺ cells were sorted and co-cultured with MSCs. Cell viability of BCMA⁺ cells was measured by MTS assay 24 h after the addition of bortezomib. The IC₅₀ of different cells was quantified. One representative of four independent experiments is shown on the left and the quantitative values of the four independent experiments are shown on the right. c Unsupervised hierarchical clustering heatmap of differentially expressed genes (DEGs) in relapsed and reversed MM patient cells. d Gene ontology analysis of the biological process (BP) and KEGG pathways on data sets obtained from relapsed and reversed MM patient cells. e Cell viability of parental, tolerant, and reversed MM1.S and RPMI-8226 cells was measured by MTS assay 24 h after the addition of bortezomib (three independent biological replicates with three technical replicates each). *P < 0.05; **P < 0.01; two-tailed t test. Data are represented as mean ± SD.