Targeted gene disruption reveals the CCK-B/gastrin receptor is not essential for development of the gastrointestinal tract, pancreas, or brain: N.A. Langhans, M. Beinborn, S. M. Quinn, M. L. Chiu, B. Ardman, and A. S. Kopin. Depts. of Medicine and Pediatrics, GRASP Digestive Disease Center, New England Medical Center/Tufts University School of Medicine, Boston MA