a Data represent the cell viability effects upon simultaneous exposure of HER2-positive and trastuzumab-conditioned (resistant) SKBR3/Tzb100 breast cancer cells to oleuropein aglycone and trastuzumab. Briefly, SKBR3 cells were incubated in serial dilutions of trastuzumab in the absence or presence of a given concentration of oleuropein aglycone. IC30 values are the concentrations of trastuzumab which decreased cell viability by 30%, measured by using a MTT assay as described in "Methods". Values are mean of three independent experiments carried out in triplicate.
b Sensitization factors were obtained by dividing the IC30 value of trastuzumab as single agent by the IC30 values obtained when oleuropein aglycone was concomitantly supplemented.