TACSTD2 and cancer: Trop-2 is overexpressed in many epithelial tumors [27], such as lung [28], pancreas [29,30], gall bladder [31], breast (the three subtypes) [32,33], urothelial and urinary bladder [34,35], prostate [36], salivary gland [37], hepatic [38], colorectal [39,40], and papillary thyroid [41] cancers.