Although significant levels of panitumumab bound to the EGFR on the tumor cell surface were measured at the single cell level at day 7 post treatment in the receptor saturation assay (Figure 4B), there was some variation between the results obtained with the tumor penetration assay and the receptor saturation assay at the earlier time points, which may reflect how the total panitumumab was detected in each assay. The gene discussed is EGFR; the disease is neoplasm.