By approaching RhoC expression from two distinct angles–its necessity for metastasis of a breast cancer cell line (SUM149), and its sufficiency to induce metastasis of a non-metastatic mammary epithelial cell line (MCF-10A)–we were able to clearly elucidate a putative role of RhoC in BCSC metastasis. This evidence concerns the gene RHOC and breast carcinoma.