CD34 and melanoma: β1-integrin has been characterised in human skin,16 CD34 has been proposed as an epithelial stem cell marker in mouse oesophagus8 and melanoma chondroitin sulfate proteoglycans (MCSP) has been identified as a potential marker for cells expressing high levels of β1-integrin.17 Consistent labelling for all of these markers was obtained in quiescent cells located at the top of the papillae (figure 2A–C).