To determine if insect and mammalian pheromone response pathways are indeed similar, we need a better understanding of the components of both pathways, particularly the mammalian one. At present progress is blocked by the lack of a high affinity ligand. A 70KDa, odorant binding glycoprotein (vomeromodulin) which is only expressed by the vomeronasal organ has been suggested to be a pheromone transporter, but again no ligand has been identified ¹²⁶. The cloning of aphrodisin which will enable the expression of large quantities of protein and the puberty accelerating effects of MUP which is already available in quantity, offer the prospect that specific binding may be obtained. This will be the first step towards elucidating the molecular mechanisms which are responsible for the fascinating behavioural effects of pheromones in mammals.