More interestingly, recent studies have illustrated that two TET1 isoforms also display distinct expression patterns, in which the full-length isoforms of TET1 are preferentially expressed in ESCs, early embryos, and primordial germ cells (PGC), while the short form of TET1 (TET1S) is restricted to somite cells and overexpressed in cancer [22, 23, 32]. This evidence concerns the gene TET1 and cancer.