Because of the well-documented clinical evidence in breast cancer [26], colorectal cancer [27,28] and other cancers [29] that overexpressed Trop-2 is associated with increased tumor aggressiveness, metastasis, and decreased patient survival, there is a growing interest in Trop-2 as a therapeutic target for solid cancers [30]. The gene discussed is TACSTD2; the disease is breast carcinoma.