While PEDF is known to exert anti-tumor activity by inhibiting angiogenesis [49,50] and inducing apoptosis [17], the present study is the first to demonstrate a link between loss of PEDF expression and the development of endocrine resistance and to show that PEDF re-expression is capable of reversing tamoxifen resistance in breast cancer. Here, SERPINF1 is linked to breast carcinoma.