Hi! Promega Corporation (Tel. (608) 247-4330) has a non-radioactive cell proliferation kit. The assay is basically a modification of the MTT assay which was developed by Mosmann some years ago (Mosmann, T. 1983. J.Immunol. Meth. 65:55). If you have any further questions, please contact me. Good Luck! Gamal E. Osman, Ph.D. gamal at u.washington.edu