In another study comparing expression of the ET-axis in a series (n=88) of invasive breast carcinomas, concomitant DCIS, and normal breast tissue, we demonstrated a stepwise increase of ET-1 and ETAR expression with disease progression, suggesting that expression of these proteins correlates with the acquisition of malignant potential and invasive behaviour (Wülfing et al, 2004a). Here, EDNRA is linked to ductal breast carcinoma in situ.