PTTG1 and esophageal squamous cell carcinoma: Another study, using 113 cases of ESCC immunohistochemistry and immunoblotting, revealed the overexpression of PTTG1. It was found that 14 tumors in 113 cases were negatively expressed; 31 cases expressed 0–10% of tumor cells (1+), 52 cases showed 10–30% tumor cell expression (2+), and 16 cases showed 30% tumor cell expression (3+).