1 Academic Unit of Clinical Oncology, Beech Hill Road, Sheffield, UK.
2 Centre for Stem Cell Research, Biomedical Sciences, Western Bank, University of Sheffield, Sheffield, UK.
3 Academic Unit of Clinical Oncology, Beech Hill Road, Sheffield, UK. P.D.Ottewell@shef.ac.uk.
4 Academic Unit of Clinical Oncology, CR-UK/YCR Sheffield Cancer Research Centre, University of Sheffield, Sheffield, S10 2RX, UK. P.D.Ottewell@shef.ac.uk.