In line with our hypothesis, histopathological studies on H&E sections revealed the presence of micro and small papillomas characterized by cellular pleiomorphism in 50% (5 out of 10) of 6 month-old Pten+/− mice (Fig. 1A, upper panel), while the gallbladder epithelium was normal in all age-matched wild type mice (0 out of 8) (Fig. 1B; Fig. S1). Here, PTEN is linked to papilloma.