Impact of TAK-243 on the p53 pathway. (A) Accumulation of p53 pathway–related proteins is demonstrated in p53 WT MM1.S cells (left panel) by western blotting, but not in TP53 mutant U266 cells (right). (B) Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas-9) methodology was used to generate MM1.S cells in which p53 expression was knocked out, or cells in which a nontargeting (NT) construct was added. These were then compared for their sensitivity to TAK-243 by measuring viability with a tetrazolium-based assay (left panel). MOLP-8 cells in which p53 had been knocked out using sequence-specific zinc finger nucleases (ZFNs) were similarly compared with MOLP-8 cells with a nontargeting ZFN (right panel). Data are presented as the mean plus or minus SD of triplicate experiments; *P < .05 when compared with controls. (C) The impact of TAK-243 on selected p53 pathway and stress-response proteins was evaluated in these p53 WT and KO cells by western blotting.