Interestingly, it has been shown that AX2 binds PtdIns(4,5)P2 and is recruited to the apical surface.26 Our previous studies had reported that silencing AX2 expression inhibited cell migration and proliferation in the pathogenesis of HPS.4, 5 Furthermore, PTEN‐mediated segregation of phosphoinositides controls cell polarization through Cdc42, which co‐localizes with the Par/aPKC/Cdc42 complex at the apical plasma membrane of epithelial cells, which is consistent with our results (Figure 6). This evidence concerns the gene CDC42 and Hermansky-Pudlak syndrome.