As a result of ERBB2 knockdown by siRNA interference, the mRNA abundance, each of CCND1, CCND3, CCNE2, CDC6, COL5A2, FN1, MMP13, TOP2A, UPA, F2R, and UPAR was decreased in the ERBB2-positive SKBR3 breast cancer cells (Fig. 2E). This evidence concerns the gene TOP2A and breast cancer.