POLD1 and neoplasm: In terms of 26 genes involved in the homologous recombination, 15 (i.e., XRCC3, XRCC2, TOP3A, RPA3, RAD54L, RAD54B, RAD51D, RAD51, RAD50, POLD3, POLD1, NBN, EME1, BRCA2, and BLM) are significantly up-regulated in OS tumor samples than normal controls (see Supplementary Fig. S1c).