EGFR and neoplasm: IHC staining of the tumor xenografts showed the heavy staining of phospho-EGFR (pEGFR) and EGFR in untreated H1975 tumor xenografts (Figure 4D; upper panel), whereas weak staining of pEGFR and EGFR was detected in HGK-treated tumor (Figure 4D; lower panel).