Many of these genes have known roles in cancer gene networks such as the proto-oncogenes JUN and FOS, RAP1A (RAS-related protein 1A), ITGB5, as well as BRCA2 (Breast cancer 2, early onset) and PCNA (Proliferating cell nuclear antigen) (Fig 7B and S2 Fig). This evidence concerns the gene PCNA and breast cancer.