CCND1 (cyclinD1) is a known critical factor in cell cycle progression, but the function of CCND1 in human cancer cell migration/invasion is not sufficiently understood despite a recent study showing that it directly regulates the focal adhesion pathway and promotes R3327 rat prostatic tumor cell migration/invasion and tumor metastasis [18] and affects cell migration and invasion in breast cancer [18–21]. The gene discussed is CCND1; the disease is breast cancer.