ESR1 and breast cancer: Aleksandra Gruslova et al., building upon previous research, demonstrated that the inhibition of FASN in endocrine-resistant breast cancer cells induces endoplasmic reticulum stress (EnRs pathway), which mediates ERα degradation, resulting in a significant decrease in ERα levels in tumor cells (P < 0.01) and the inhibition of the growth of TAM-resistant breast cancer cells (169).