Professor Martin has greatly advanced contemporary understanding of calcium regulating hormones. He demonstrated that osteoclasts possess calcitonin receptors and clarified the second messenger actions of parathyroid hormone (PTH). He has contributed extensively to modern concepts of bone cell biology, being a co-proposer of the hypothesis that bone resorbing hormones act initially on osteoblastic cells. His most outstanding contribution was the cloning of parathyroid hormone related protein (PTHrP) which he has shown to have a pivotal role in the syndrome of the humoral hypercalcaemia of malignancy as well as being involved in an increasingly diverse series of biological events.