POLD2 and breast cancer: Particularly interesting are the genes PGAM2 [51], GCK [52], and OGDH [53], which encode enzymes of the glycolysis and the tricarboxylic acid cycle, as well as POLM [54] and POLD2 [55], which encode DNA polymerase μ and a subunit of DNA polymerase δ, respectively, suggesting a possible co-regulation of energetic metabolism and DNA replication genes in breast cancer.