PAD2 has been shown to mediate histone citrullination in various types of cancer, such as prolactinoma, multiple myeloma (PAD2-CitH3R6), breast cancer MCF-7 (PAD2-CitH3R2, 8, 17), and prostate cancer (PAD2-CitH3R26), where, particularly in prostate cancer, its expression is required for the survival and cell cycle development of prostate cancer cells [10]. This evidence concerns the gene PADI2 and breast cancer.