XBP1 and breast cancer: The XBP1-IGFBP3 signaling pathway promotes invasion and metastasis in NSCLC.[41] Urra et al found that ATF4-mediated activation of lysosomal-associated membrane protein 3 promotes metastasis in breast cancer cells in a hypoxic environment, and ATF4 is upregulated in esophageal cancer, which increases matrix metalloproteinases to promote cell invasion and metastasis.[42] Additionally, triple-negative breast cancer cells with high expression of XBP1 are more likely to metastasize to the lung.