Especially, PN4 is considered to be essential for suppressing tumor growth via making fiber capsule surrounding cancer cells, and should not be inhibited in cancer [15] Based on the above, we have reported the importance of inhibiting only pathological POSTN (PN1–3) but not physiological POSTN (PN4) [6,7,8,13,16,17,18], and especially, we showed the inhibition effect of the antibody for POSTN exon 17, which PN1 and PN3 have, on mice breast cancer cells [16]. Here, POSTN is linked to breast cancer.