Through in vitro and in vivo experiments, they demonstrated that prostate cancer cells induce osteocytes to produce growth-derived factor 15 (GDF15) which, in turn, enhanced the expression of the early growth response 1 (EGR1) transcription factor in prostate cancer cells and regulated the growth and the invasive properties of cancer cells in a positive feedback loop [50]. The gene discussed is EGR1; the disease is cancer.