(A) U266, RPMI-8226, and MM1.S cells were incubated in the presence or absence of DMSO (solvent control) or MO-OH-Nap for 48 hours. Immunoblot analysis of phosphorylated eIF2α (p-eIF2α), eIF2α, ATF4, IRE1α, and PERK was performed along with β-tubulin as a loading control. Densitometric analysis of UPR proteins (normalized to β-tubulin) for the treated cells normalized to DMSO (solvent control) cells is shown. (B) U266 cells were incubated for 24 or 48 hours with solvent control, SAHA, or MO-OH-Nap in triplicate. RNA was isolated, cDNA prepared, and PCR was performed using XBP-1-specific primers. The upper band represents unspliced XBP-1 and the lower band represents spliced XBP-1. (C) qRT-PCR analysis of CHOP expression in U266 and MM1.S cells incubated in the presence or absence of DMSO (solvent control) or MO-OH-Nap for 24 or 48 hours. Data represents fold change normalized to DMSO control. (n = 3 independent experiments, error bars denote standard error, *denotes p < 0.05. **denotes p < 0.01).