During a malignant transformation, the membrane expression of the MUC1 cell surface-associated oncoprotein often changes from apical to circumferential simultaneously with a loss of polarity of the epithelial cells, acting as anti-adhesive molecules and facilitating the detachment of malignant cells, and increasing the metastatic and invasive potential of tumour cells [12]. The gene discussed is MUC1; the disease is neoplasm.