Cell viability assay

Cells were seeded in 384 well plates at a density of 5000 cells per well in 25 μL medium. Drug treatment was performed 2 hours post-thawing by adding increasing doses of drug from a 3-fold dilution series to test 11 different concentrations. Each dose was added in four replicate wells, and the plate was incubated at 37°C. Following selinexor treatment, cell viability was assessed 48 h post-drug treatment by adding PrestoBlue reagent (ThermoFisher) and measuring fluorescence using a SpectraMax i3 multi-mode plate reader (Molecular Devices). Following nutlin-3a treatment, cell viability was assessed 72 h post treatment by adding Cell Titer Glo 2.0 (Promega) and measuring luminescence in a SpectraMax i3 multi-mode plate reader. For drug combinations of selinexor and MK-2206, or selinexor and nutlin-3a, cells were seeded in 384-well plates followed by drug treatment using a 3-fold serial dilution of selinexor and a 5-fold serial dilution of either MK-2206 or nutlin-3a. Cell viability was assessed 72 h post drug treatment by adding Cell Titer Glo 2.0 (Promega) and measuring luminescence in a SpectraMax i3 multi-mode plate reader.