RAD21 and breast cancer: Atienza et al9 showed that the expression of Rad21 in breast cancer cells is 1.25‐2.5 times higher than in normal breast tissue and that knockdown of Rad21 decreases Rad21 mRNA levels, inhibits cell proliferation, promotes apoptosis, and increases the sensitivity of MCF‐7 cells to etoposide and bleomycin.