BCL2 and esophageal squamous cell carcinoma: Numerous studies have delved into the in vitro and in vivo consequences of metformin on ESCC and EAC cells, with predominant emphasis on two pathways: the signal transducer and activator of transcription 3 (Stat3)/Bcl-2 pathway [54,55,56] and the phosphoinositide 3-kinase (PI3K)/AKT/mTOR pathway [57].