PIK3CA/mTOR pathway (# 4EBP1 is inactivated by phosphorylation) a). Immunohistochemistry was performed for phosphorylated AKT, pS6 and p4EBP1. b) Outcome of immunohistochemical staining integrating PIK3CA mutation status. Numbers indicate the amount of cases showing positive immunohistochemical staining. Mutations are signified by (n*), with n = number of cases. mTOR, mammalian target of rapamycin.