Fig. 1. Synergistic effect of small interfering RNA (siRNA) and interferon beta (IFN-β) to inhibit the growth of human papilloma viruse type 18-positive HeLa cells. The viability of HeLa cells decreased in proportion to the concentration of each Sp-18E6/27 siRNA and IFN-β. The combination of Sp-18E6/27 siRNAs and IFN-β produced the synergistic inhibitory effect to HeLa cell growth in low concentrations of IFN-β of 1 and 2 mM. ^*P<0.05.