A process is provided to deliver polynucleotide-based gene expression inhibitors to cells in a mammal in vivo for the purpose of inhibiting gene expression in the cells. Inhibition is sequence-specific and relies on sequence similarity to of the polynucleotide-based gene expression inhibitor and the target nucleic acid molecule. Delivery of the polynucleotide-based gene expression inhibitor can enhance the efficacy of co-delivered small molecule drugs.