 PIK3R2 and PIP5K1A are two kinases that phosphorylate Phosphatidylinositol (PIP) providing PSD4 with substrates for its GTP loading ability.PSD4 as a guanine exchange factor, loads ARL14/ARF7 with GTP.Subsequently, ARF7EP interacts with MYO1E which binds itself to actin myofibers.