The interaction between β4 integrin and FAK was identified in the malignant triple-negative breast cancer cell line (MDA-MB-231) (Fig. 1a) as well as in the metastatic colon cancer cell line (HCT-116) (unpublished data), but not in the non-tumorigenic breast epithelial cell line (MCF10A) or other cancer cell lines (i.e., MCF7, MDA-MB-435, A549, and HeLa). This evidence concerns the gene PTK2 and triple-negative breast carcinoma.