Objective:To determine whether p27,PTEN and Ki-67 these 3 proteins are related to the tumor by study the situation they express in thymoma.Methods:52 patients with thymoma who were confirmed by clinical pathology were selected,12 normal patients were also selected,the situation of these 3 proteins were detected by immunohistochemical method.Results:p27expression decreased in thymus tumor tissue(benign,aggressive thymic tumor),the difference was statistically significant(P<0.05),and the expression of Ki-67 a...