PAD1 generally associates with epidermis and uterus but also nervous tissue; PAD2 is the most ubiquitously expressed isozyme and detected in most tissues; PAD3 relates to skin, hair follicles and the nervous system; PAD4 mainly to white blood cells and cancers and PAD6 mainly associates with embryonic tissues [10,11,12]. Here, PADI2 is linked to cancer.