Figure 4: IHC analysis of pS6 and pERK expression in patients with negative (blue) staining and strong positive (brown) staining of tumor cells with pERK and pS6. Normal patient skin samples with minimal background staining and normal appearing cells. Representative actinic keratosis (AK) patient samples showing weak, cytoplasmic staining. Representative BCC patient samples with negative (blue) staining and few scattered positive (brown) staining of tumor cells. Representative SCC patient samples with strong positive (brown) nuclear and cytoplasmic staining with pERK and pS6. Note that the stroma stains positive (brown) in BCC, whereas the tumor stains negative (blue).