PIKFYVE and cancer: Although selective inhibition of PIKFYVE will suppress the biosynthesis of both PIP2 and PIP3 in PIKFYVE-dependent cancer cells, the primary pathway for biosynthesis of PIP2 (and consequently PIP3) is phosphorylation of PI4P by PIP5K1 isozymes, because PI(3,5)P2 is about 125-fold less abundant than PIP2 [44].