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). Here, GRB2 is linked to cancer.