1. Supplemental Figure 1: Chemical structures of fludioxonil and fenhexamid. FludioxonilFenhexamid

2. Supplemental Figure 2: Fludioxonil and fenhexamid do not affect control genes used in Q-PCR. MCF-7 cells were ‘serum-starved’ for 72 h prior to treatment with DMSO (vehicle control), fludioxonil (Flu) or fenhexamid (Fen), as indicated for 6 h. A) RNU38 and B) RNU48 are used as controls in miRNA Q-PCR. C) GAPDH and D) 18S rRNA are used as controls in mRNA Q-PCR. Values are the mean ± SEM of 9 experiments. RNU38 17 18 19 20 21 22 23 DMSO100nM Flu100nM Fen GAPDH 16 17 18 19 20 21 22 DMSO100nM Flu100nM Fen RNU48 17 18 19 20 21 22 23 DMSO100nM Flu100nM Fen 18S 11 12 13 14 15 16 17 DMSO100nM Flu100nM Fen CT value

3. Supplemental Figure 3: Fludioxonil and fenhexamid do not decrease ER  protein in MCF-7 cells. MCF-7 cells were seeded in 6-well plates and were ‘serum starved’ for 72 h prior to treatment with DMSO (vehicle control), 10 nM E 2, 100 nM fludioxonil (Flu), 100 nM fenhexamid (Fen), or 100 nM 4- hydroxytamoxifen (4-OHT, an ER antagonist) for 48 h. 30  g protein from whole cell lysates were separated by 10 % SDS-PAGE and immunoblotted for ER . Membranes were stripped and re-probed for  -actin as a loading control. Immunoreactive bands were quantified and the ratio of ER  -actin normalized to the DMSO control is indicated.

4. Supplemental Figure 4: Fludioxonil and fenhexamid do not stimulate apoptosis in MCF-7 cells. MCF-7 cells were seeded in 6-well plates and cultured in phenol red-free IMEM +5% DCC-FBS for 48 h prior to treatment with DMSO (vehicle control), 10 nM E2, 100 nM fludioxonil (Flu), 100 nM fenhexamid (Fen) for 96 h. 30  g protein from whole cell lysates were separated by 10 % SDS-PAGE and immunoblotted for PARP. Membranes were stripped and re-probed for  -tubulin. Intact (116 kDa) and cleaved (85 kDa) PARP were measured and the percentage of PARP cleavage was calculated from the formula % PARP cleavage = C/ C+F *100 where C = the 85 kDa cleaved band and F = the full length 116 kDa band. DMSO E2 Flu Fen PARP 116kDa  -tubulin PARP 85kDa 0 1 2 3 4 5 6 7 DMSO E2 % PARP cleavage 150- 75- Fen Flu

5. Supplemental Figure 5: Fludioxonil and fenhexamid have antiestrogenic activity in MCF-7 cells. MCF-7 cells were serum-starved for 48 h and then treated with DMSO, 10 nM E2, 100 nM fludioxonil, or 100 nM fenhexamid, alone or in combination, as indicated for 6 h. CCND1 (cyclin D1), PGR (progesterone receptor, PR), ESR1 (ER  ), and ESR2 (ER  ) expression was determined by Q-PCR. Values are the average of triplicate determinations within one representative experiment. Statistical analysis used one way ANOVA followed by Dunnett’s Multiple Comparison Test. * P < 0.05 versus DMSO (control). # p < 0.05 versus 10 nM E 2. CCND1PGRESR1ESR2 Relative mRNA Expression * * 0.0 0.5 1.0 1.5 2.0 DMSOE2FluFenE2 + FluE2 + Fen * * * * * * * * * * # ## # # # # #

6. Supplemental Figure 6: Fludioxonil and fenhexamid do not affect 18S rRNA control gene expression in MCF-7 cells. MCF-7 cells were ‘serum-starved’ for 72 h prior to treatment with DMSO (vehicle control), 10 nM E2, or 100 nM fludioxonil or 100 nM fenhexamid, as indicated for 24 h. 18S rRNA was used as a control for RT-Q-PCR for Figure 6. Values are the mean +/- SEM of triplicate determinations. 18S rRNA CT values 12 13 14 15 16 DMSOE2100nM Flu 100nM Fen E2 + FluE2 + Fen CT

7. Supplemental Figure 7: Fludioxonil and fenhexamid do not increase cyclin D1 expression in ER  -negative MDA-MB-231 cells. MDA-MB-231 cells were serum-starved for 48 h and then treated with DMSO, 10 nM E2, 10 or 100 nM fludioxonil or fenhexamid, as indicated for 6 h. CCND1 (cyclin D1), BCL2, PGR (progesterone receptor, PR) expression was determined by Q-PCR. PGR was not expressed in MDA-MB-231 (CT values > 38). Values are the average of triplicate determinations within one representative experiment. Statistical analysis used one way ANOVA followed by Dunnett’s Multiple Comparison Test. * P < 0.05 versus DMSO (control). MDA-MB-231 DMSO E2 10 nM Flu 10 nM Fen 100 nM Fen RelativeExpression 100 nM Flu 0.0 0.5 1.0 1.5 2.0 2.5 CCND1 BCL2 * * * * * *