To extend the findings in the HaCaT cell line to other tumour cell lines, we determined CCL20 expression in established tumour cell lines of breast cancer (n = 6), melanoma (n = 13) as well as head and neck squamous cell carcinoma (HNSCC) (n = 14), compared with the corresponding benign precursor cells, namely human primary mammary epithelial cells, human primary melanocytes and human primary mucosal keratinocytes (Fig. 1d–f). Here, CCL20 is linked to breast cancer.