TKTL1 and neoplasm: TKTL1 is an enzyme activated by the promotor DNA hypomethylation [13,14], which plays a key role in the non-oxidative arm of the pentose phosphate pathway (PPP) leading to an increased production of lactate, acidification of the tumor microenvironment, and degradation of the stroma, thus facilitating the cell migration and the development of metastasis [15].