ENPP2 and hepatocellular carcinoma: Autotaxin (ATX), which was initially isolated as a prometastatic enzyme from the conditional medium of human melanoma cells [1], is over-expressed in several human cancers and contributes to their progression, such as non-small cell lung cancer, breast cancer, renal cell cancer, prostate cancer, hepatocellular carcinoma, thyroid cancer and neuroblastoma [15].