Effect of knockdown of ZAR2 in synchronized MCF7 cells on the BRCA2 and ZAR2 mRNA levels (A) and on the activities of BRCA2 and ZAR2 gene promoters (B) at the G0/G1 phase. ZAR2 was knocked down in MCF7 cells with two different double-stranded stealth siRNAs (Invitrogen). Levels of the mRNAs were determined by real-time RT-PCR. Promoter activities were measured in MCF7 cells transiently transfected with the single-reporter constructs (Fig. 1B) following the dual luciferase assay protocols (Promega). pGL3-Control was used as normalization control as described in the 'Methods' section. Results are mean ± SE (n = 6). '*' indicates the difference between the corresponding control and the experimental sets is statistically significant (p < 0.001).