ANXA5 and ovarian cancer: To evaluate the potential role of PAX2 in apoptosis, allophycocyanin-Annexin V staining, which detects an increase of phosphatidylserine residues in the outer plasma membrane leaflet during the early stages of apoptosis was used to measure apoptotic cells in RMUGL and TOV21G ovarian cancer cell lines with PAX2 knockdown (Figure 4c).