REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
β-actin	Cell Signaling	Cat#4970; RRID: AB_2223172
SRP9	Proteintech	Cat#11195–1-AP; RRID: AB_2239820
SRP14	Proteintech	Cat#11528–1-AP; RRID: AB_2194708
TSG101	Proteintech	Cat#14497–1-AP; RRID: AB_2208090
GFP	Abcam	Cat#ab6673; RRID: AB_305643
GFP	Abcam	Cat#ab13970; RRID: AB_300798
RPC32	Santa Cruz	Cat#sc-21754; RRID: AB_675824
RIG-I	Cell Signaling	Cat#3743; RRID: AB_2269233
ISG15	Santa Cruz	Cat#sc-50366; RRID: AB_2126309
FLAG	Sigma	Cat#F1804; RRID: AB_262044
HA	Santa Cruz	Cat#sc-7392; RRID: AB_627809
c-MYC	Abcam	Cat#ab32072; RRID: AB_731658
NICD1	Cell Signaling	Cat#4147; RRID: AB_2153348
NICD1	Abcam	Cat#ab8925; RRID: AB_306863
NOTCH2	Cell Signaling	Cat#5732; RRID: AB_10693319
NICD3	Chris Siebel	N/A
NOTCH4	Cell Signaling	Cat#2423; RRID: AB_2151366
CD11c-FITC	BioLegend	Cat#117306; RRID: AB_313775
CD44-PerCp-Cy5.5	BioLegend	Cat#103031; RRID: AB_2076206
MHCII-BV421	BioLegend	Cat#107631; RRID: AB_10900075
CD40-BV711	BD Biosciences	Cat#740700;
CD11b-APC	BD Biosciences	Cat#553312; RRID: AB_398535
CD45.2-AF700	BioLegend	Cat#109822; RRID: AB_493731
CD86-APC-Cy7	BioLegend	Cat#105030; RRID: AB_2244452
PDL1-PE	BD Biosciences	Cat#558091; RRID: AB_397018
CD8a-PE-ef610	eBioscience	Cat#61–0081-80; RRID: AB_2574523
F4/80-PE-Cy7	BioLegend	Cat#123114; RRID: AB_893478
Bacterial and Virus Strains
Sendai virus Cantell	Mercado-López et al., 2013,Carolina Lopez	N/A
One Shot Stbl3 Chemically Competent E. coli	ThermoFisher	Cat#C737303
DH5α Competent Cells E. coli	ThermoFisher	Cat#18265017
BL21 Competent E. coli	NEB	Cat#C2530H
Biological Samples
Patient serum	Obtained through the UPENN RadOnc Biosample Repository or the Breast Program Translational Resource Center. Informed consent and HIPAA authorization was procured for all study subjects.	N/A
Serum from healthy volunteers	Innovative Research	Cat#IPLA-SERS
Cancer-associated fibroblasts	Tchou et al., 2012, Julia Tchou	N/A
Chemicals, Peptides, and Recombinant Proteins
Recombinant RIG-I	Devarkar et al., 2016, Joseph Marcotrigiano	N/A
Recombinant SRP9	This paper	N/A
DAPT	Sigma	Cat#D5942
TEV Protease	Sigma	Cat#T4455
Glutathione Sepharose 4 Fast Flow	GE Healthcare	Cat#17–5132-01
L-Glutathione	Sigma	Cat#G4251
4-Thiouridine	Sigma	Cat#T4509
Micrococcal Nuclease	NEB	Cat#M0247S
ProLong Diamond Antifade Mountant with DAPI	ThermoFisher	Cat#P36962
D-Luciferin	PerkinElmer	Cat#122796
RNA Polymerase III Inhibitor (ML-60218)	Millipore	Cat#557403
4-Hydroxytamoxifen	Sigma	Cat#H7904
5-(and-6)-carboxyf luorescein diacetate, succinimidyl ester (CFSE)	ThermoFisher	Cat#C34554
Critical Commercial Assays
Click-iT RNA Alexa Fluor® 488 Imaging Kit	ThermoFisher	Cat#C10329
Anti-FLAG M2 Magnetic Beads	Sigma	Cat#M8823
EnzChek Phosphate Assay Kit	ThermoFisher	Cat#E6646
NEBNext Ultra Directional RNA Library Prep Kit	NEB	Cat#E7420L
MEGAshortscript T7 Transcription Kit	ThermoFisher	Cat#AM1354
Dynabeads MyOne Streptavidin C1	ThermoFisher	Cat#65001
SYTOX Red Dead Cell Stain	ThermoFisher	Cat#S34859
Vybrant Multicolor Cell-Labeling Kit	ThermoFisher	Cat#V22889
Deposited Data
ExoRNA-seq, MNase-seq, 5’ppp-seq, Patient ExoRNA-seq	This paper	GEO: GSE93078
ISG-R and ISG-NR gene expression data	Boelens et al., 2014	GEO: GSE60998
Stromal and breast cancer gene expression data from laser-capture micro-dissection	Finak et al., 2008	GEO: GSE9014
Experimental Models: Cell Lines
MDA-MB-231 (1833)	Kang et al., 2003, Yibin Kang	N/A
MDA-MB-231 (4175 LM2)	Minn et al., 2005	N/A
MDA-MB-436	ATCC	ATCC HTB-130
HCC1937	ATCC	ATCC CRL-2336
MCF7	ATCC	ATCC HTB-22
MDA-MB-468	ATCC	ATCC HTB-132
MRC5	ATCC	ATCC CCL-171
BJ	ATCC	CRL-2522
KB1P	Liu et al., 2007, Jos Jonkers	N/A
MYC-ER MEF	Gomez-Roman et al., 2003, Costas Koumenis	N/A
Adult Lung Fibroblasts	Harvested from adult lung of C57BL/6 mouse	N/A
Experimental Models: Organisms/Strains
Mouse: C57BL/6	Charles River	Stock#027
Mouse: NU/J (athymic nude, nu/nu)	The Jackson Laboratory	Stock#002019
Oligonucleotides
ERCC RNA Spike-In Mix	ThermoFisher	Cat#4456740
See Table S5 for all primers used in qRT-PCR	This paper	Table S5
See Table S6 for all adaptors used for 5’ triphosphate RNA sequencing.	This paper	Table S6
See Table S7 for all gene targeting sequences by RNAi and CRISPR/Cas9	This paper	Table S7
See Table S8 for all in vitro transcribed RNA sequences.	This paper	Table S8
Recombinant DNA
Plasmid: pGFH-9	Katharina Strub	Addgene #39538
Plasmid: pGFH-14c	Katharina Strub	Addgene #39541
Plasmid: pUltra-hot	Malcom Moore	Addgene #48139
Plasmid: pUltra-hot-SRP9-14	This paper	N/A
Plasmid: pOZ-N-FH	Roger Greenberg	N/A
Plasmid: pOZ-N-RIG-I-WT	This paper	N/A
Plasmid: pOZ-N-RIG-I-MUT	This paper	N/A
Plasmid: pCMV-dR8.2 dvpr	Bob Weinberg	Addgene #8455
Plasmid: pCMV-VSV-G	Bob Weinberg	Addgene # 8454
Plasmid: PX458	Feng Zhang	Addgene #48138
Plasmid: pCT-CD81-RFP	SBI	Cat#CYTO125-PA-1
Plasmid: pET His6 GST TEV LIC cloning vector (1G)	Scott Gradia	Addgene #29655
Plasmid: pET His6 GST TEV-SRP9	This paper	N/A
Software and Algorithms
R language and environment for statistical computing and graphics		https://www.r-project.org
Bioconductor and packages		https://www.bioconductor.org
CRAN		https://cran.r-project.org/web/packages/
cutadapt		https://pypi.python.org/pypi/cutadapt
bowtie2		http://bowtie-bio.sourceforge.net/bowtie2/index.shtml
STAR		https://github.com/alexdobin/STAR/releases
Subread		http://subread.sourceforge.net
DESeq2		https://www.rdocumentation.org/packages/DESeq2
flowCore		http://bioconductor.org/packages/release/bioc/html/flowCore.html
Rtsne		https://cran.r-project.org/web/packages/Rtsne/index.html
mclust		https://cran.r-project.org/web/packages/mclust/vignettes/mclust.html
RNAstructure		http://rna.urmc.rochester.edu/RNAstructure.html