BRCA1 and breast cancer: Therefore, our results showing that MERIT40 is overexpressed in BC (Fig. S2), that MERIT40 overexpression overstimulates HR activity (Fig. 2) and is associated with a poor prognosis (Fig. 5A), and that altered MERIT40 expression is associated to aneuploidy (Fig. 6) suggest that MERIT40 overexpression, as that of BRCA1, plays an important role in BC development by overstimulating HR.