Among the various breast cancer cell lines, we found that CNKSR1 was highly expressed in a HER2-positive breast cancer cell line, SKBR-3, and protein expression of CNKSR1 was low in MCF-7 (luminal-type), MDA-MB-231 (basal-type), and MDA-MB-453 (HER2-positive–type) cells (Fig 5A). This evidence concerns the gene ERBB2 and breast carcinoma.