Supplementary Figure S3 from Palazestrant (OP-1250), A Complete Estrogen Receptor Antagonist, Inhibits Wild-type and Mutant ER-positive Breast Cancer Models as Monotherapy and in Combination

OP-1250 acts as a selective ER degrader (SERD) in wild-type and ESR1 mutant cell lines. A, B, Representative blot images from the simple western assay shown in Figure 3 (see main article) after 24-h treatment with 300 nM compound or 1 nM E2 with indicated compound treatments and cell lines. C, D, Representative blot images from simple western assay of MCF7 cells treated for 2 h, 4 h, or 8 h with the listed concentrations of compounds in the presence or absence of MG-132 and simple western analysis of ERα protein levels after treatment with listed compounds. Samples were normalized to untreated control, with mean and SD across at least three independent experiments shown. E, F, ERα degradation in CAMA-1 cells with the indicated homozygous mutant as assessed by simple western assay after 24-h treatment with 300 nM compound or 1 nM E2. Samples were normalized to untreated control, represented by a dotted line, with mean and SD across at least three independent experiments shown. G, H, Representative blot images from simple western data shown in panels E and F with indicated compound treatments and cell lines.