McDowell, N Activin has direct long-range signalling activity and can form a concentration gradient by diffusion. [electronic resource] - Current biology : CB Sep 1997 - 671-81 p. digital Publication Type: Journal Article; Research Support, Non-U.S. Gov't ISSN: 0960-9822 Standard No.: 10.1016/s0960-9822(06)00294-6 doi Subjects--Topical Terms: ActivinsAnimalsBlastocyst--physiologyCell DifferentiationDNA-Binding Proteins--physiologyDiffusionFetal ProteinsGrowth Substances--physiologyIn Situ HybridizationInhibins--physiologyMesoderm--cytologyRNA, Messenger--metabolismSignal TransductionT-Box Domain ProteinsTranscription Factors--physiologyTransforming Growth Factor beta--physiologyXenopusBrachyury Protein