Subsequently, increased GRB2 levels activate phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) and extracellular regulated protein kinases (ERK)/mitogen-activated protein kinases (MAPK) signaling pathways, promoting the progression of esophageal squamous cell carcinoma (90). Here, AKT1 is linked to esophageal squamous cell carcinoma.