1. Department of Pulmonary Medicine, University of Texas MD Anderson Cancer Center, Houston, TX 77030, U.S.A.
2. Cystic Fibrosis Research and Treatment Center, University of North Carolina, Chapel Hill, NC 27599, U.S.A.
3. Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA 02114, U.S.A.
4. Department of Medicine, University of Colorado School of Medicine, Aurora, CO 80045, U.S.A.
5. Department of Biostatistics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, U.S.A.
6. Experimental Immunology Branch, National Cancer Institute, Bethesda, MD 20892, U.S.A.