Fig. S1 siControl E2 G1: 45.7% S: 26.9% G2-M: 27.4% siER  E2 G1: 70.9% S: 9.9% G2-M: 19.2% G1: 57.1% S: 12.0% G2-M: 30.9% siRNF31 E2 A B siRNF31 siControl siRNF31+ ERα plasmid G1: 57.6% S: 22.6% G2-M: 20.3% G1: 61.7% S: 13.8% G2-M: 24.9% G1: 55.4% S: 18.9% G2-M: 26.2%

Fig. S2 siControl siRNF31 T47D RNF31 ER  GAPDH RNF31 ER  GAPDH siControl siRNF31 MDAMB kDa 66 kDa 37 kDa 120 kDa 66 kDa 37 kDa 120 kDa 66 kDa 37 kDa siControl siRNF31 SMARTpool siRNF31 oligo 1 RNF31 ER  GAPDH A B siRNF31 oligo Relative mRNA level RNF31 (mRNA)

Fig. S3 AB DC NA *** Relative luciferase activity NA Relative luciferase activity Relative mRNA level NA Relative mRNA level ***

Input IP: RNF31 IB: ER  IP IgG IP RNF31 Input IP IgG IP ER  IP: ER  IB: RNF31 Fig. S4 A B Input IgG IP RNF31 ER  IgG Input IgG IP RNF31 Ig G ER  Ig G Input IgG IP RNF31 C Input IgG IP ERα RNF31 Ig G RNF31 Ig G RNF31

Fig. S5 nucleus cytosol

Fig. S6 RNF31 ER  Merge Merge with nuclear stain

Fig. S7 Fold enrichment over IgG control 

Gene nameSequence RNF31 ForwardACCCCCTATTGAGAGAGATTGCT RNF31 ReverseTGGAGCCTGGGACAGAGG ERα ForwardGCT ACG AAG TGG GAA TGA TGA AAG ERα ReverseTCT GGC GCT TGT GTT TCA AC PS2 ForwardCAT CGA CGT CCC TCC AGA AGA G PS2 ReverseCTC TGG GAC TAA TCA CCG TGC TG Cyclin D1 Forward CAC GCG CAG ACC TTC GT Cyclin D1 Reverse GGG CGG ATT GGA AAT GAA C ADORA1 Forward GGA TCG ATA CCT CCG AGT CA ADORA1 Reverse GAG AAT CCA GCA GCC AGC TA 36B4 Forward GGCGACCTGGAAGTCCAACT 36B4 Reverse CCATCAGCACCACAGCCTTC PKIB Forward CHIP TCA CTG CGG GAT ATT GGC TTA PKIB Reverse CHIP AGC TGG TCT TCT TCC TCC TAA ACT G ADORA1 Forward CHIP GAT GGA TGG GAA CAC ATT GGT ADORA1 Reverse CHIP TGG TGG CGG AGC ACA AA ERα Forward CHIP GGG ATC GCT CCA AAT CGA ERα Reverse CHIP CTT GCC CTG ACA TTG GCT TAA PS2 Forward CHIP CCT CCC GCC AGG GTA AAT AC PS2 Reverse CHIP CCG GCC ATC TCT CAC TAT GAA 18S Forward CHIP GCTTAATTTGACTCAACACGGGA 18S Reverse CHIP AGCTATCAATCTGTCAATCCTGTC Real-time PCR primers used in this study Table S1

TCGA KMplot.com All samples Symbolr2r2 P-valueSymbolr2r2 P-value ACE ACE ADA ADA ADORA ADORA APOA APOA AREG AREGNA AURKA AURKA BTG BTG CCNG CCNG CSF1R CSF1R CYP1A CYP1A ESR ESR GJB GJB2NA GREB GREB HMOX HMOX IGFBP IGFBP KCNMA KCNMA PDZK PDZK1NA SGK SGK3NA TFF TFF TGFB TGFB ACE ACE ACPP ACPP CAV CAV CCNE CCNE CD CD CDKN1A CDKN1A CXCL CXCL CXCL CXCL CXCR CXCR CXCR CXCR CYP19A CYP19A CYP1B CYP1B EGFR EGFR EGR EGR NR5A NR5A PPARA PPARA REL REL S100A S100A TRPV TRPV WISP WISP Table S2 RNF31 expression correlates with expression of known ERα target genes Yellow: p-value < 0.05; Red: positive correlation; Green: negative correlation