Suppression of IGF-1R with OSI-906 sensitizes 8226.BR cells to bortezomib. (A) RPMI 8226.wt and 8226.BR cells were simultaneously treated with increasing concentrations of OSI-906 alone (left), or with OSI-906 and 10nM bortezomib combined (right) for 24 hours, followed by measurement of live cells with WST-1. Error bars represent the SD of triplicate experiments. (B) Induction of apoptosis was assessed in single samples of 8226.wt and 8226.BR cell lines treated with OSI-906 for 24 hours and stained with annexin-V–FITC and TOPRO-3. Multiple myeloma cells (2 × 10⁴) isolated from a pleural effusion of a patient displaying bortezomib resistance were cotreated with increasing concentrations of bortezomib and 1μM OSI-906 (C), or increasing concentrations of OSI-906 and 10nM bortezomib alone (D) for 24 hours, and examined using the WST-1 assay. Data presented are representative of triplicate experiments, and error bars are ± SD.