Aberrant Trop-2 overexpression has been described in various solid cancers, including those with low Trop-2 expression in their normal counterparts (e.g. colorectal, renal, lung, and breast carcinomas) (reviewed in Goldenberg et al. [1] and Shvartsur and Bonavida [7]). Here, TACSTD2 is linked to breast carcinoma.