AuNP-T cells enhance the delivery of gold nanoparticles to the tumor site in vivo. Tumor-bearing mice were injected i.v. with PEG-AuNPs or AuNP-T cells. Tumors were subsequently resected at various time points and measured for AuNP content using ICP-MS. Values displayed represent the percentage of injected gold normalized for tumor dry weight differences (mean ± SEM). The percentage of gold delivered by the AuNP-T cells at 48 h represents a significant, four-fold increase over the PEG-AuNP group at 24 h (P < 0.01).