PIN1 and breast neoplasm: Moreover, ATO reduced the levels of Pin1 and its substrate oncoproteins such as NF-κB/p6554, β-catenin55, and Rab2A34, and increased the levels of Pin1 substrate tumor suppressors such as Fbw756 in breast tumors derived from xenografts expressing Pin1 or M130I mutant, but not M130V mutant (Fig. 3j).