IGF1R and esophageal squamous cell carcinoma: Studies of ESCC demonstrated that upon binding to its ligands IGF‐1 or IGF‐2, IGF‐1R is autophosphorylated and the phosphorylation activates the downstream pathways of PI3K/AKT/mTOR and Ras/Raf/MEK/MAPK 9, 10, which promote tumor cell proliferation, invasion, metastasis, and evasion of apoptosis 10, 11.