Because inflammation is a crucial factor in skin tumour development (Johansson et al., 2008; Zamarron and Chen, 2011) and EPI−/− skin has an abnormal number of DETCs and CD4+CD3+ lymphocytes (Sevilla et al., 2007), we examined whether the inflammatory response to short term TPA treatment was altered in skin with a defective epidermal barrier. The gene discussed is CD4; the disease is skin neoplasm.