Considering that: (1) these ligands bind to albumin (Fig. 1B, 2A-B, Supplementary Fig. 1A-B); (2) the high levels of protein accumulation in the tumor interstitium due to the enhanced permeability and retention effect [15-17]; and (3) the potential influence of protein-drug binding on drug bioavailability [7], we examined the cellular targeting and uptake of 14C-Dp44mT, 14C-Bp4eT and 14C-PIH in the presence and absence of the serum proteins, HSA, BSA or Tf (Fig. 3A-C). The gene discussed is TF; the disease is neoplasm.