RB1 and breast cancer: While the constituent genes in RBNSig-OV showed a limited overlap of four genes (RB1, CCNE2, FAM111B, and TYMSOS) with the RBNSig of breast cancer (RBNSig-BC), the RBNSig-BC genes showed similar expression profile in ovarian cancer albeit with smaller effect size, suggesting similarities in the biology of RB1-defective cancers of breast and ovary (fig.