Intercellular communication in multicellular organisms enables cells to respond to environmental changes. Intercellular signal transduction transmitters include hormones, peptide growth factors, neurotransmitters as well as some lipid-soluble mediators. Once signalling molecules are bound to their cell surface receptors, one or more intracellular signals are generated which alter the Qehavior of the target cell. The IXth International Washington Spring Symposium at the George Washington University in Washington, D.C. was organized to assess the current status of the field of signal...