PIK3CA and invasive ductal breast carcinoma: Here we demonstrate that acinar-to-ductal metaplasia, PanINs and invasive pancreatic ductal adenocarcinomas can arise secondary to activating mutations in Pik3ca. Pc1Pik3cap110* mice develop metaplasia surrounded by an inflammatory reaction within the pancreas by 10 days of age; these lesions progress to PanINs and even invasive ductal adenocarcinomas by 20 days of age.