Figure 1.

Modification of PtdIns Mediated by PI3K, PTEN, SHIP, INPP4 and the PI3K signaling pathway in cancer: The phosphorylated state of inositol lipids inserted in the cell membrane is controlled by inositol kinase and phosphatase enzymes. As proposed in “The Two PIP hypothesis” [22], the presence of both PI(3,4,5)P₃ and PI(3,4)P₂ at the membrane triggers downstream signaling events that more effectively promote cancer cell survival. Downstream targets of AKT are both pro-survival (activation of mTORC1, RAF) and anti-apoptotic (inhibition of GSK-3, FOXO) permitting increased cancer cell survival and proliferation.