ESR1 and cancer: Bis-2(5H)-furanone derivatives show acceptable antiproliferative activity against cancer cell lines, including C6 (rat glioma cell), EC-1 (human esophageal carcinoma cell), MDA-MB-231 (estrogen receptor-negative human breast cell), MCF-7 (estrogen receptor-positive human breast cell), HepG2 (human hepatoma cell), and CNE-1 (nasopharyngeal carcinoma cell) [43].