**7. Acknowledgements**

The authors acknowledge gratefully the support of NIH grants 5R01HL069049 (C.H.M., A.A.B), 5R21/R33HL089038 (C.H.M., A.A.B); 5R01HL082600 (C.H.M.); 1R01CA917794 (A.A.B.), and 1RO1CA109557 (A.A.B.), 5RO1EB000350 (A.A.B.) and Bayer Hemophilia Award (C.H.M.). We thank Drs. Thomas J. Matula, Wayne Kreider, Michael R. Bailey, Peter J. Kaczkowski, Mark Borden, Misty Noble, Sophia Song and Ms. Hong Chen for helpful discussions during preparation of this manuscript.
