NPPA and breast carcinoma: Cancer cell interaction with E-selectin seems to be the initial step for CTC extravasation and is essential for metastasis.8 It has been reported that bone vascular E-selectin directly captures breast cancer cells to promote bone metastasis.9 Consistently, atrial natriuretic peptide (ANP) prevents cancer metastasis by suppressing E-selectin expression by ECs.10 Subsequently, ICAM-1 and VCAM-1 on ECs allow adhesion of cancer cells to ECs.