In this study, we tested HA-PEI/HA-PEG CD44 targeted nanoparticle for MDR1 siRNA in ovarian cancer MDR cells with anticipation that this delivery system will result in the lowering of the apoptotic threshold necessary for augmenting the efficacy of paclitaxel in a MDR ovarian cancer model. Here, ABCB1 is linked to ovarian cancer.