M ost G protein–coupled receptors (GPCRs) probably exist as homodimers, but it is increasingly recognized that GPCRs may also dimerize with other types of GPCRs and that this physical interaction may affect the function of either receptor. A study in this issue of the JCI demonstrates how heterodimerization between prostaglandin E receptors and β₂–adrenergic receptors (β₂ARs) in airway smooth muscle cells results in uncoupling of β₂ARs and a diminished bronchodilator response to β₂AR agonists (see the related article beginning on page 1400). This illustrates what we believe to be a novel mechanism of receptor cross-talk and highlights the potential importance of GPCR heterodimerization in diseases such as asthma and how this could lead to the development of more specific therapies in the future.