Among the four subtypes of BC—HER2-positive, luminal A, luminal B, and triple-negative—securin shows higher expression in estrogen receptor (ER) negative BC tissues than in ER-positive tissues 42, with significant upregulation observed in the triple-negative breast cancer (TNBC) subgroup compared to other subgroups 43, 44. Here, PTTG1 is linked to breast cancer.