In MCF7 human breast cancer cells known to express epithin/PRSS14, similar ~ 14 kDa proteolytic fragment was observed using the anti-N antibody raised against the human epithin/PRSS14 intracellular domain (Fig. 2d), indicating that the generation of the EICD may be the general phenomena in epithin/PRSS14-expressing cells. Here, ST14 is linked to breast cancer.