TACSTD2 and breast cancer: Also, the presence of 2 different TROP2 IHC expressionpatterns (membranous/cytoplasmic) in BC reflects that TROP2 biological function is fundamental to deciphering the discrepancy between TROP2 protein8 and TACSTD2 gene expression; where membranous localization of TROP2 protein is associated with adverse tumor features, while the intracellular (cytoplasmic) TACSTD2 gene expression is associated with a favorable impact in HR+/HER2− BC.