This assumption is technically difficult to test directly with high precision, although immunolabeling of flank tumor xenograft sections with the pY1068 antibody demonstrated EGFR phosphorylation in almost all cells in tumor sections with the predominant localization of the phosphorylated receptor at the plasma membrane (Figure 3B and Figure 3—figure supplement 1B). The gene discussed is EGFR; the disease is neoplasm.