Cell migration drives cell invasion and metastatic progression in prostate cancer and is a major cause of mortality and morbidity. However the mechanisms driving cell migration in prostate cancer patients are not fully understood. We previously identified the cancer-associated cell migration protein Tetraspanin 1 (TSPAN1) as a clinically relevant androgen regulated target in prostate cancer. Here we find that TSPAN1 is acutely induced by androgens, and is significantly upregulated in prostate cancer relative to both normal prostate tissue and benign prostate hyperplasia (BPH). We also show for the first time, that TSPAN1 expression in prostate cancer cells controls the expression of key proteins involved in cell migration. Stable upregulation of TSPAN1 in both DU145 and PC3 cells significantly increased cell migration and induced the expression of the mesenchymal markers SLUG and ARF6. Our data suggest TSPAN1 is an androgen-driven contributor to cell survival and motility in prostate cancer.Cancer, in its most aggressive form, is not only a disease of uncontrolled cell growth, but also a disease of inappropriate cell migration. Activating invasion and metastasis is a hallmark of cancer progression 1, 2 and is the leading cause of mortality among cancer patients 3 . Metastasis involves cancer cells detaching from the primary tumour, and travelling as circulating tumour cells through the bloodstream or lymphatic system to other parts of the body. Prostate cancer is the most common male cancer in Europe, with around 50,000 new cases in the UK each year 4 . At initial diagnosis 37-43% of men have late stage disease and 17-34% of prostate cancer patients have metastasis (http://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/ prostate-cancer/incidence#ref-8). The development of prostate cancer is initially driven by androgen steroid hormones via the androgen receptor (AR) transcription factor. The first line treatment for prostate cancer that is no longer organ confined is androgen deprivation therapy (ADT). However, after 2-3 years many patients develop