Further analysis of PAD2 expression in tamoxifen-resistant breast cancer cell line MCF7 (MCF7/TamR) subclones confirmed that PAD2 was significantly (P = 9.39 × 10− 13) upregulated compared to the tamoxifen-sensitive controls (MCF7/TamS) (Fig. 1b). The gene discussed is PADI2; the disease is breast cancer.