ART4 and prostate cancer: The main difference between tumor and normal cells is the expression ratio and the type of carbohydrates on their cell surfaces marked as tumor-associated carbohydrate antigens (TACAs) conditioned in two main groups: glycoprotein antigens (TACAs are bound to proteins), widespread in epithelial cancers, and glycolipid antigens (TACAs are bound to ceramides) shared by melanoma, lung, ovarian, breast, colon, and prostate cancers [24].