The present invention relates to a method for providing molecules that are capable of inhibiting angiogenesis, comprising the steps of providing a range of molecules; testing whether these molecules can prevent interaction between JAM-B and JAM-C; testing the positive molecules for their ability to block angiogenesis in vivo; and selecting molecules that are positive in the angiogenesis test as angiogenesis inhibiting molecules. The method may further comprise the step of isolating or producing the angiogenesis inhibiting molecules. The invention further relates to the angiogenesis inhibiting molecules thus provided and produced, to their use in the treatment of cancer, to therapeutical compositions comprising them. In a particular embodiment the invention relates to monoclonal antibodies, in particular MAb H33, to soluble JAM-C and JAM-B and to small molecules.