Phosphatidylinositol 3,4-bisphosphate

[3][4][5] These kinases and phosphatases conduct phosphorylation and dephosphorylation at the inositol sugar head groups 3’, 4’, and 5’ positions, producing differing phosphoinositides, including PtdIns(3,4)P2.

[3][9][10] PtdIns(3,4)P2 has been indicated to be critical for AKT (Protein kinase B, PKB) activation within the PI3K pathway through the PI’s regulation by the SHIP1 and 2 phosphatases.

Yet the 5-phosphatase SHIP proteins synthesis of PI(3,4)P2 has been linked to tumor cell survival due to the lipid’s binding and subsequent activation of Akt.

[16] Akt activation causes downstream metabolism alterations, apoptosis suppression and a rise in cell proliferation.

[19] Recently, PtdIns(3,4)P2 has been shown to play an important role in vesicle maturation during clathrin-mediated endocytosis (CME).

[3][22] PI(3,4)P2 plays another possible role at the PM, promoting cytoskeletal rearrangements through actin regulatory proteins like Lamellipodin.