ESR1 and breast carcinoma: As warheads of estrogen receptors, the following ligands (4-OHT, Raloxifene, estradiol, lasofoxifene) were used, while MV1 and bestatin were used as IAPs warheads, as shown in Figure 14D. SNIPER(ER)-19 (4-OHT-MV1, which had 4-OHT as estrogen receptor warhead and MV1 as IAP warhead) at 30 nM decreased the ER-α levels in MCF-7 breast cancer cells.