The combination of nifuroxazide and the MEK inhibitor UO126 results in enhanced cytotoxicity of MM cells and enhanced loss of STAT3 tyrosine phosphorylation. (A) U266 cells were incubated with the indicated concentrations of nifuroxazide and UO126 for 48 hours. Viability was measured using an ATP-dependent bioluminescence assay. (B) U266 cells were incubated with the indicated concentrations of nifuroxazide and UO126 for 24 hours. Western blots were performed for tyrosine-phosphorylated STAT3, serine-phosphorylated STAT3 (p-ser STAT3), and total STAT3.