We found that ROR1 is expressed by most human cancers, including breast cancer, intimating that it plays a role in cancer pathophysiology.7 In support of this proposition are findings demonstrating that expression of ROR1 can enhance epithelial–mesenchymal transition and cancer-cell proliferation, migration, and metastasis.8,9 Moreover, high-level tumor-cell expression of ROR1 associates with adverse outcome in patients with various cancers.8,10–12. This evidence concerns the gene ROR1 and cancer.