extremely significantP <0.01
As shown in Figure 4 , compared with the controls which were MCF-7/ADR cells with no inhibitor pretreatment, the cellular uptake efficiency of PAMAM-NH 2 in MCF-7/ADR cells increased to an extremely significant degree with the addition of VRP ( P <0.01) and to a significant degree with the addition of FTC ( P <0.05), but the addition of MK571 effected no change in such efficiency.