NDRG2 and Cushing syndrome: Using the Mann-Whitney test, we found that the expression of NDRG2 had no correlation with age, gender, presence or absence of repeated surgery, secreting or non-secreting PAs and Cushing syndrome (p = 0.076, p = 0.545, p = 0.783, p = 0.927 and p = 0.980, respectively).