XYLT2 and cancer: Furthermore, since PI3K integrates both the ErbB2/Grb2/SOS/RAS and ErbB3/p85 pathway, the ErbB2-overexpressing cancer cells become addicted to the PI3K signalling hub, as manifested by increased susceptibility to PI3K inhibitors (Supplementary Fig. 5A), compared with ErbB3 inhibition (Fig. 7b).