Since the expression of ATX is increased in some specific cancers, such as breast cancer, glioblastoma, teratocarcinoma [20], non-small-cell lung cancer [21], thyroid carcinoma [22], and melanoma [23], it is possible that the serum ATX isoform concentration might change in certain cancers originating from particular tissues or cells. This evidence concerns the gene ENPP2 and breast cancer.