PTGER4 and neoplasm: Ep4, which was derived from a P51 tumor pathologically assigned to the luminal type because of their weakly positive progesterone receptor (PR) without ER expression (Allred scores: ER, 0; PR, 3; Fig. 2b), had low VIM activity but the high activity of EGFR and relatively low activity of luminal keratins (Fig. 2d, e and Supplementary Fig. 2b).