Granta.MI63R (A) and H929.63R (B) cells were incubated with MI-63 or RITA for 24- and 48-hours. In parallel, Granta.MI63R (C) and H929.63R (D) cells were exposed to MI-63 and RITA simultaneously, or first to MI-63 for 24-hours followed by RITA and MI-63 for 48-hours, or to RITA first for 24-hours followed later by MI-63 and RITA for 48-hours. Cell viability was determined using the WST-1 reagent, and results were expressed relative to the vehicle control. An unpaired T test was performed on conditions in panels C and D, where * designates p<0.05 relative to the vehicle control, and # designates p<0.05 relative to the simultaneous addition of RITA and MI-63.