For 4T1 cells, total RNA was isolated using the Purelink RNA Mini Kit (Invitrogen), and mRNA was enriched using the NEBNext Poly(A) mRNA Magnetic Isolation Module (NEB). For MDA-MB-231-D3H2LN-luc cells, total RNA was extracted using the RNeasy kit (Qiagen). For 4T1 cells, the KAPA Stranded mRNA-seq kit (Roche) was used to prepare libraries for mRNA-seq. For MDA-MB-231-D3H2LN cells, libraries were prepared from 1 µg of total RNA for each sample using the KAPA mRNA HyperPrep Kit (Roche) and Illumina adapters (NEB).