PTPRZ1 and breast carcinoma: The expression levels of both PTN and PTPRZ1 were significantly downregulated in the breast cancer group compared to the normal group (p < 0.05) (Fig. 1a, b), and there was no significant correlation between the expression levels of PTN and PTPRZ1 (p > 0.05, R2 = 0.00048) (Fig. 1c).