BRCA2 and ovarian cancer: Figure 1a demonstrates the expression of PARP1 enzyme following treatment with the DNA damaging agent hydrogen peroxide (H2O2) at 20 mM, in different ovarian cancer cell lines in terms of BRCA2 status. In comparison to untreated cells, there was a 28.8-fold increase in PARP1 expression in PEO1cells, which lack functional BRCA2. In contrast, PARP1 expression increased 5-fold for PEO4 cells, 12.5-fold for MDAH-2774 and 15.3-fold for SKOV3, all with functional BRCA2 (Figure 1a).