Fig. 2. IMR90 cells require a higher dnPLK1:endogenous PLK1 ratio to elicit the equivalent apoptotic response to SAOS-2. Both of the cell types were infected with dnPLK1 at 62.5, 125, 250, and 500 MOI. Percentage increase in Sub-2N DNA content was determined by flow cytometry. One in four dilutions of dnPLK1 Ad cell lysates were compared with control virus lysates to determine fold overexpression of dnPLK1 protein. For each 2-fold increase in MOI, SAOS-2 cells showed a 1.5-fold increase in dnPLK1 level, whereas IMR90 cells showed a 2-fold increase.