Figure 8. LS1 enhances killing of yeast by etoposide. LS1 enhances etoposide (ETOP) cytotoxicity in cells overexpressing TOP2. (A) Cells expressing native levels of TOP2 are not sensitive to ETOP in the presence of LS1. Cells contained an empty CEN plasmid Ycp50. (B) Overexpression of TOP2 (YCPpDED1-TOP2) increased sensitivity to ETOP in the presence of LS1. Yeast strain YMM10 , which contains gene deletions in several drug efflux pumps, was used to promote ETOP sensitivity.