Fig. (2) The production of PIP₃ is a critical signalling hub. GPCR's and receptor tyrosine kinases expressing a YxxM motif recruit PI3K to the plasma membrane via interactions with SH2 domains. PI₃ kinases then catalyse the formation of PIP₃ from PI-4,5-P₂. PIP₃ then acts on a variety of downstream effectors expressing PH domains to promote cellular responses.