REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
Phospho-Stat3 (Tyr705) (D3A7) XP® Rabbit mAb	Cell Signaling Technology	Cat#9145; RRID: AB_2491009
Stat3 (79D7) Rabbit mAb	Cell Signaling Technology	Cat#4904; RRID: AB_331269
Phospho-NF-κB p65 (Ser536) (93H1) Rabbit mAb	Cell Signaling Technology	Cat#3033; RRID: AB_331284
NF-κB p65 (C22B4) Rabbit mAb	Cell Signaling Technology	Cat#4764; RRID: AB_823578
β-Actin (8H10D10) Mouse mAb	Cell Signaling Technology	Cat#3700; RRID: AB_2242334
C/EBPβ (LAP) Antibody	Cell Signaling Technology	Cat#3087; RRID: AB_2078052
Anti-rabbit IgG, HRP-linked Antibody	Cell Signaling Technology	Cat#7074; RRID: AB_2099233
Anti-mouse IgG, HRP-linked Antibody	Cell Signaling Technology	Cat#7076; RRID: AB_330924
Chemicals, peptides, and recombinant proteins
D-Luciferin, Potassium Salt	Gold Biotechnology	LUCK-100
Cypridina Luciferin TFA salt	Nanolight	305-1
SuperSignal™ West Pico PLUS Chemiluminescent Substrate	ThermoFisher	34577
SuperSignal™ West Femto PLUS Chemiluminescent Substrate	ThermoFisher	34095
Matrigel matrix	Corning	356234
Crystal violet solution	Sigma	V5265
Critical commercial assays
RNeasy Mini Kit	QIAGEN	217004
5×All-In-One RT MasterMix Kit	Abm	G485
PowerUp™ SYBR™ Green Master Mix	ThermoFisher	A25742
Novex™ WedgeWell™ 10%, Tris-Glycine gel	ThermoFisher	XP00100PK2
Nitrocellulose Membrane, 0.45 μm	Bio-Rad	1620115
Pierce™ BCA Protein Assay Kit	ThermoFisher	23225
RIPA Buffer	Boston Bioproducts	#BP-115
Halt™ Protease and Phosphatase Inhibitor Cocktail	ThermoFisher	78441
24 mm Transwell® with 8.0 μm Pore Polycarbonate Membrane Insert	Corning	3428
Deposited data
TCGA breast cancer dataset	TCGA-BRCA	https://portal.gdc.cancer.gov/projects/TCGA-BRCA
Experimental models: Cell lines
MDA-MB-231	ATCC	HTB-26
ErbB2 parental and brain metastatic cell lines	Joan Massague laboratory	Muller et al. 1988; Valiente et al. 2014
MDA-MB-231parental and metastatic cell lines	Ichiro Nakano laboratory	Yamashita et al. 2020
MCF7	ATCC	HTB-22
Experimental models: Organisms/strains
Mouse: Athymic Nude-Foxn1nu	Envigo	6904F
Oligonucleotides
Primers for qPCR, see Table S1	MGH primerbank	https://pga.mgh.harvard.edu/primerbank/
Recombinant DNA
pLKO.1-puro Mammalian shOR5B21 Transduction Particles	Sigma	TRCN0000203498
pLKO.1-puro Mammalian shRNA Control Transduction Particles	Sigma	SHC016
pLenti-GIII-CMV-GFP-2A-Puro-OR5B21	Abm	LV247930
pLenti-CMV-GFP-2A-Puro-Blank Vector	Abm	LV590
Software and algorithms
imageJ	National Institutes of Health	https://imagej.nih.gov/ij/
Graphpad prime 7.0a	Graphpad	https://www.graphpad.com/
Adobe Illustrator CS6	Adobe	https://www.adobe.com/products/illustrator/