ERBB2 and breast cancer: TNS1 amplification has been reported in sporadic colorectal carcinomas (53 cases) [149], while co-amplification of TNS4 within the 17q21.2 locus, which encompasses GJC1, IGFBP4, TNS4, and TOP2A, was observed in ER-positive/HER2-amplified breast cancers (70 cases), suggesting potential oncogenic cooperativity [150].