The altered expression of 8 skin epithelial cell-associated genes (KRT1, KRT5, KRT15, KRTDAP, DSP, PKP1, PERP and SBSN) that displayed >two-fold decreased expression in the M MCTs have previously been associated with the metastasis of a non-epithelial tumour as they were expressed at lower levels in human metastatic cutaneous melanomas than in primary tumours [71]. Here, PKP1 is linked to neoplasm.