-The expression of HML-2 and its co-correlation with other genes, such as proline dehydrogenase (PRODH), suggests its involvement in tumorigenesis, particularly in germ cell tumors [124]. The epigenetic regulation of HML-2 expression and its potential role as a cis-regulatory element highlights the possibility of targeting HML-2 to regulate tumor-specific gene expression [62,125]. Here, PRODH is linked to germ cell tumor.