Immunohistochemical analyses of various signaling molecules in MAPK and PI3K pathways. Representative examples of immunohistochemical staining patterns observed in invasive breast cancers. p-AKT (a) shows predominant nuclear staining with weak cytoplasmic staining in this case. PI3K-p110α (b), p-S6 (c), p-RAF (d), and HSP90 (e) show strong cytoplasmic staining. The p-p70S6K (f), p-p44/42 MAPK (g), and PTEN (h) are localized in both cytoplasmic and nuclear compartments.