ESR1 and breast cancer: In addition, EVs with miR-221, miR222, lncRNA UCA1, and mitochondrial RNA can spread endocrine resistance between BC cells via mechanisms such as decreasing ER-α expression, increasing CSC levels, increasing cell viability, and awaking dormant therapy-induced cancer stem-like cells, but their relationship with hypoxia needs further elucidation [207, 213, 214] (Fig. 4C).