Significant variations in the intensity of EGF-Rh (Figure 6) and pY1068 fluorescence (Figure 3 and Figure 3—figure supplement 1B) relative to the EGFR-GFP signal have not been observed within the tumor, providing no indications that there is a significant population of cells which are exposed to ligand concentrations that would result in qualitatively different EGFR activation and behaviors. The gene discussed is EGF; the disease is neoplasm.