We have focused on the aPKC-PAR complex that plays a central role on cell polarity regulation. We found that KIBRA, an upstream regulator of the Hippo pathway, directly associates with aPKC and suppress the kinase activity. Further, KIBRA negatively regulates exocytosis of apical proteins through negative regulation of aPKC.

Another example is ASPP2, an upstream regulator of the aPKC-PAR complex. We have identified a novel protein that connect E-cadherin and the aPKC-PAR complex at the cell-cell contact. Identification of the role of these polarity regulators on the maintenance of mammary stem/progenitor cells is our current subject.