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 head and neck squamous cell carcinoma.