Plinabulin inhibits growth and triggers apoptosis in MM. (A) Human MM cell lines MM.1S, MM.1R, RPMI-8226, and INA-6 were treated with plinabulin (dose range, 0.001-10μM) for 24, 48, and 72 hours; cell viability was measured with MTT assays. Data presented are mean ± SD of 3 independent experiments (P < .05 for all the cell lines at different time points). (B) MM.1S, MM.1R, RPMI-8226, and INA-6 cell lines were treated with plinabulin (8nM) for 48 hours, and apoptosis was measured with Annexin V/PI binding assay by flow cytometry (P < .05; n = 3). A representative graph from 3 independent experiments is shown. Right quadrant: top panel, Annexin V⁺/PI⁺ cells; bottom panel, Annexin V⁺.