During progression through normal-AK-SCC-Metastasis, we found a significant reduction in the proportion of Normal Keratinocyte Differentiated cells (NKD) and an increase in the proportion of TSKs (Fig. 1e, f) and the appearance of a Tumour Keratinocyte Differentiated population (TKD) at the AK stage (Fig. 1e, f). The gene discussed is TSKS; the disease is neoplasm.