To determine the relative abundance of the Ki‐67 mRNA isoforms terminated at the different PASs in the breast cancer cells, we performed RT‐qPCR using primers flanking different regions of the Ki‐67 3′UTR (F1/R1, F2/R2, F3/R3, F4/R4, F5/R5, and F6/R6; Fig. 1C). This evidence concerns the gene MKI67 and breast cancer.