REAGENT or RESOURCE	SOURCE	IDENTIFIER
Antibodies
Anti-ATF4	Cell Signaling	Cat# 11815; RRID: AB_2616025
Anti-ATF6	Cell Signaling	Cat# 65880; RRID: AB_2799696
Anti-BARD1	Thermo Fisher	Cat# 22964-1-AP; RRID: AB_2879190
Anti-BRCA1	Novus Biologicals	Cat# AF2210; RRID: AB_2067618
Anti-BRCA1	Santa Cruz Biotech	Cat# sc-6954; RRID: AB_626761
Anti-Cyclophilin B	Abcam	Cat# ab 178397
Anti-Cyclophilin B	ThermoFisher	Cat# MA5-31392; RRID: AB_2787028
Anti-DERLIN 1	Santa Cruz Biotech	Cat# sc-293385
Anti-DERLIN 1	Origene Technologies	Cat# TA301554
Anti-GAPDH	Cell Signaling	Cat# 2118; RRID: AB_561053
Anti-IRE1	Cell Signaling	Cat# 3294; RRID: AB_823545
Anti-IRE1 (phospho)	Abcam	Cat# ab124945; RRID: AB_11001365
Anti-IRE1	Santa Cruz Biotech	Cat# sc-100772; RRID: AB_1124115
Anti-PERK	Cell Signaling	Cat# 5683; RRID: AB_10841299
Anti-PERK (phospho)	Abcam	Cat# ab192591; RRID: AB_2728666
Anti-PERK	Santa Cruz Biotech	Cat# sc-377400; RRID: AB_2762850
Anti-SEL1L	Santa Cruz Biotech	Cat# sc-377350
Anti-Ubiquitin agarose beads conjugated	Santa Cruz Biotech	Cat# sc-8017; RRID: AB_628423
Anti-Ubiquitin	Cell Signaling	Cat# 43124; RRID: AB_2799235
Anti-Flag M2 affinity gel	Millipore Sigma	Cat# A2220; RRID: AB_10063035
Anti-Strep-tactin	Neuromics	Cat# 2-1502-001
Anti-GRP94	Cell Signaling	Cat# 2104; RRID: AB_823506
Anti-BiP	Cell Signaling	Cat# 3177; RRID: AB_2119845
Anti-HSP70	Cell Signaling	Cat# 46477; RRID: AB_2687559
Anti-eIF2a	Cell Signaling	Cat# 5324; RRID:AB_10692650
Anti-eIF2a (phospho)	Cell Signaling	Cat# 3398; RRID: AB_2096481
Bacterial and virus strains
CellLight ER GFP, BacMam 2.0	Thermo Fisher	Cat# C105090
Chemicals, peptides, and recombinant proteins
Tetraphenylethene maleimide	AIEgen Biotech	Cat# AIETM TPE-MI
Concanavalin-A TRITC conjugated	Thermo Fisher	Cat# C860
Bortezomib	SelleckChem	Cat# S1013
UBE1	R&D Systems	Cat#E−305-025
UBE2J1	R&D Systems	Cat# E2-750
BRCA1	Active Motif	Cat# 31113
Ubiquitin	Boston Biochem	Cat# K-200B
Cyclosporin A	SelleckChem	Cat# S2286
NIM811	MedChem Express	Cat# HY-P0025
Alisporivir (Debio-025)	MedChem Express	Cat# HY-12559
Critical commercial assays
NE-PER Nuclear and Cytoplasmic Extraction Reagents	Fisher	Cat# 78835
Quick-RNA Miniprep kit	Zymo Research	Cat# R1054
SuperScriptTM III First-strand Synthesis SuperMix	Fisher	Cat# 11-752-050
SYBR Green Supermix	Bio-Rad	Cat# 1725121
Endoplasmic Reticulum Isolation Kit	Sigma	Cat# ER0100
Deposited data
https://data.mendeley.com/datasets/72gjb45yjv/1
Experimental models: Cell lines
MDA-MB-436 BRCA1-def	ATCC	Cat# HTB-130; RRID: CVCL_0623
MDA-MB-436 BRCA1-replete (BRCA1+)	Johnson et al., 2013	NA
HCC-1937 BRCA1-def	ATCC	Cat# CRL-2336; RRID: CVCL_0290
HCC-1937 BRCA1-replete (BRCA1+)	Zhang et al., 2004	NA
SUM140PT BRCA1-def	Asterand Biosciences	Cat# SUM149PT; RRID: CVCL_3422
UWB1.289 BRCA1-def	ATCC	Cat# CRL-2945; RRID: CVCL_B079
UWB1.289 BRCA1 replete ∗BRCA1+)	ATCC	Cat# CRL-2946; RRID: CVCL_B078
MDA-MB-231	ATCC	Cat# HTB-26; RRID: CVCL_0062
MCF7	ATCC	Cat# HTB-22; RRID: CVCL_0031
HEK293	ATCC	Cat# CRL-1573; RRID: CVCL_0045
MCF10A	ATCC	Cat# CRL-10317; RRID: CVCL_0598
Experimental models: Organisms/strains
Athymic nude mice	Jackson Laboratories	Cat# 002019; RRID: IMSR_JAX:002019
Oligonucleotides
EIF1AK3	OriGene	Cat# HP208096
ERN1	OriGene	Cat# HP205316
BRCA1	OriGene	Cat# HP210038
BARD1	OriGene	Cat# HP200444
GAPDH	OriGene	Cat# HP205798
sp XBP1 forward primer, 5′- TGCTGAGTCCGCAGCAGGTG -3′; reverse primer, 5′- GCTGGCAGGCTCTGGGGAAG -3′	NM_001079539.1	Fung et al., 2014
Total XBP1 forward primer, TTGTCACCCCTCCAGAACATC. reverse primer, TCCAGAATGCCCAACAGGAT
Control siRNA	Dhamarcon	Cat# D-001810-10-20
BRCA1 siRNA	Dhamarcon	Cat# sL0034610000
CypB siRNA (pooled)	Santa Cruz Biotech	Cat# sc-35145
CypB-A siRNA	Santa Cruz Biotech	Cat# sc-35145a
CypB-B siRNA	Santa Cruz Biotech	Cat# sc-35145b
CypB 3′UTR siRNA	Horizon Discovery	Cat# CTM-710441
DERLIN-1 siRNA	Santa Cruz Biotech	Cat# sc-60519
IRE1 siRNA	Santa Cruz Biotech	Cat# sc-40705
BiP siRNA	Santa Cruz Biotech	Cat# sc-29338
GRP94 siRNA	Santa Cruz Biotech	Cat# sc-35523
HSP70 siRNA	Santa Cruz Biotech	Cat# sc-29352
PERK siRNA	Santa Cruz Biotech	Cat# sc-36213
PDI siRNA	Santa Cruz Biotech	Cat# sc-36201
Recombinant DNA
pLenti PGK V5-LUC Neo plasmid	Addgene	Cat# w623-2; RRID: Addgene_21471
BRCA1/pcDNA3.1	Yeung et al., 2008	NA
BARD1	Sino Biologicals	Cat# HG15850-CF
PERK	OriGene	Cat# RC214993
IRE1	OriGene	Cat# RC215023
PPIB	OriGene	Cat# RC203180
NSP15	OriGene	Cat# VC100587
Software and algorithms
ImageJ	Schneider et al., 2012	https://imagej.nih.gov/ij/
GraphPad v.7.04	Prism software	https://www.graphpad.com/
Living Image v.4.7.3	PerkinElmer	https://www.perkinelmer.com/lab-products-and-services/resources/in-vivo-imaging-software-downloads.html#LivingImage
FlowJo-Win64–10.8.0	FlowJo	https://www.flowjo.com/solutions/flowjo/downloads