PROTAC ER Degrader-4 is a von Hippel-Lindau-based PROATC estrogen receptor (ER) degrader, binding to ER with an IC50 of 0.8 nM. PROTAC ER Degrader-4 induces ER degradation in MCF-7 cells with an IC50 of 0.3 nM.In Vitro: PROTAC ER Degrader-4 shows equal to 100% ER degradation at 0.3 μM in the MCF-7 ER degradation cellular assay.