Notably, XBP1 and transmembrane protein 26 (TMEM26), both upregulated in the treatment‐resistant cohort, exhibited high expression levels in HR+/HER2− breast tumors compared with other subtypes (Figure1A,B), suggesting their potential association with resistance to endocrine therapy plus CDK4/6 inhibitors in this subtype. The gene discussed is CDK4; the disease is breast neoplasm.