CBX2 and ovarian carcinoma: Gui et al. evaluated the role of 12 PcG proteins in primary and recurrent ovarian cancer and found that immunohistochemistry (IHC) demonstrated significantly higher levels of CBX2 expression in recurrent tumors compared to primary tumors at presentation (primary ovarian tissue at presentation n = 100, recurrent disease at relapse n = 50, p < 0.001)16.