JPT1 and neoplasm: We describe here a semiquantitative proteomics investigation of matched tumor tissues from the same cohort of pre‐ and post‐metformin‐treated patients collected during our preoperative study of metformin in obese EC patients and identification of Jupiter microtubule‐associated homolog 1 (JPT1) as a predictive and pharmacodynamic biomarker of metformin response in EC patients.