GPNMB and neoplasm: As the specific activity is equivalent in both studies (185 MBq/mg), the 20 μg-injected dose in the post-PET biodistribution study likely saturated gpNMB and, thus, yielded a lower % ID/g at 7 days p.i. To test this hypothesis, we then conducted a biodistribution study in a small subset of mice injected with 2 μg (0.37 MBq) of [89Zr]DFO-CR011 at 7 days p.i. to determine if a lower mass of antibody would increase tumor uptake.