Acknowledgements
We would like to thank Andras Nagy for providing the R1 ES cell line, Janet Rossant for the 129SvJ mouse genomic DNA library, and Ralph Zirngibl for modification of the pPNT vector. Initial cloning of Capn2 and vector construction was undertaken by DEC as a sabbatical visitor at Queen's University with support from the National Science Foundation (MCB9723636) and the University of Maine.
This work was supported by grants from the Canadian Institutes of Health Research and The Heart and Stroke Foundation of Canada. P.D. was an Ontario Graduate Scholar.