Fig. 2
From: Targeting phosphoinositide 3-kinase (PI3K) in head and neck squamous cell carcinoma (HNSCC)
Interactive signaling pathway of EGFR-PI3K-mTOR. PI3K binds to cytoplasmic tail of receptor tyrosine kinase via SH domains within p85 regulatory subunit. Activation signal can also be transferred through Ras-binding domain in p110 catalytic subunit which tethers PI3K molecule to Ras protein in growth receptors. p110 activation by Ras binding is inhibited by p85 subunit which can be released by co-stimulation of SH domain by tyrosine kinase [151]