PTGER1 and prostate carcinoma: Also recent studies characterising EP receptor expression in a variety of tumour types showed that expression of EP1 is increased in tumour cells relative to normal tissue (Shoji et al, 2004; Miyata et al, 2006; Rask et al, 2006) and is associated with tumour progression and metastasis in prostate cancer (Miyata et al, 2006).