OBJECTIVES: Epithelial-mesenchymal transition (EMT) is known to play an important role in the development of tumor invasion and progression in tumors of epithelial origin. Our aim was to investigate the role of tight junction proteins, Par3/Par6/atypical protein kinase C (APKC), Discs large (Dlg), and Scribble in human bladder pathogenesis. METHODS: We evaluated levels of APKC, Dlg, and Scribble in 92 superficial bladder tumors using tissue microarrays and immunohistochemistry, and correlated expression with pathologic variables and clinical outcomes. RESULTS: There was a slight apparent enrichment in strong vs. weak staining for APKC (54.9% vs. 45.1%), Dlg (65.7% vs. 34.3%), and a marked enrichment for Scribble (75% vs. 25%) in the superficial bladder tumors. Univariate analysis determined that both tumor focality and APKC expression were significantly associated with tumor recurrence (P < 0.05). Multivariate analysis using the Cox's proportional hazards model revealed that only APKC (P = 0.025) as well as tumor focality (P = 0.018) were independent and significant prognostic factors for tumor recurrence in all patients. We found that no immunohistochemical staining of any of the cell polarity proteins significantly predicted for tumor progression on either univariate or multivariate analysis. CONCLUSIONS: Loss of APKC expression in superficial bladder tumors is a strong predictor of tumor recurrence.