Higher levels of β‐catenin expression in the normal glands of PIK3CA‐mutant mice (Fig. S1F), and reports that PIK3CA‐H1047R caused an expansion of the luminal progenitor population (Tikoo et al., 2012), led us to hypothesize that the Wnt signaling pathway is likely to be activated in the PIK3CA‐H1047R human breast tumors. The gene discussed is PIK3CA; the disease is breast neoplasm.