We showed that K1 is present on the surface of MCF-7 breast cancer cells, and a comparison of the total K1 levels in cell lysates using Western blot showed that cancer cells (MCF-7 and MDA-MB-435) have a much higher expression of K1 compared to non-cancerous breast tissue derived epithelial (MCF-10A) cells [25]. This evidence concerns the gene KRT1 and breast carcinoma.