PTPRJ and neoplasm: However, in areas where the tumor retained partial glandular/tubular architecture, PTPRJ delineated the lumina (Fig. 2E, black arrowheads) i.e. showed the apical staining of luminal cells observed in normal breast samples (Fig. 2A-C) or in normal areas of tissue adjacent to the tumor (Fig. 2D, grey arrowheads).