The expression of N-cadherin, characteristic of various cancers, very often leads to changes in the cells' adhesive properties. Thus, we sought to find out if N-cadherin expressed in various, but cancer-related cells, differs in its functional properties that could contribute to variations in cells' phenotypes. In our work, measurements of an unbinding force of a single N-cadherin molecule, probed with the same antibody both on a surface of living non-malignant (HCV29) and malignant cells (T24) of bladder cancer, were carried out with the use of an atomic force microscopy. The results show the enhanced N-cadherin level in T24 malignant cells (8.7% vs. 3.6% obtained for non-malignant one), confirmed by the Western blot and the immunohistochemical staining. The effect was accompanied by changes in unbinding properties of an individual N-cadherin molecule. Lower unbinding force values (26.1 ± 7.1 pN) in non-malignant cells reveal less stable N-cadherin complexes, as compared to malignant cells (61.7 ± 14.6 pN). This suggests the cancer-related changes in a structure of the binding site of the antibody, located at the extracellular domain of N-cadherin. Copyright © 2011 John Wiley & Sons, Ltd.