Modulating agents and methods for enhancing or inhibiting classical cadherin-mediated functions are provided. The modulating agents comprise at least a tryptophan-containing cell adhesion recognition sequence of a classical cadherin molecule, a conservative analogue or peptidomimetic thereof, or an antibody or fragment thereof that specifically binds to such a cell adhesion recognition sequence. Modulating agents may additionally comprise one or more cell adhesion recognition sequences recognized by cadherins and/or other adhesion molecules. Such modulating agents may, but need not, be linked to a targeting agent, pharmaceutically active substance and/or support material.