Finally, the clinical impact of PRL pathway and polarity proteins in relation to breast cancer patient outcome was confirmed as the expression of PRLR positively correlates with most core polarity proteins and a gene signature of PRLR together with the highest correlated polarity genes PATJ, PALS1 and Dlg1 showed significant prognostic value, correlating with better OS and RFS in large breast cancer datasets. Here, DLG1 is linked to breast carcinoma.