Abstract: We discuss the categorical structure of a tube, let say a homogeneous one over a tame hereditary algebra over a field (or, more generally, over a noncommutative regular projective curve), and compare a bottom-up with a top-down approach for its determination. We compare the functorial properties of the Auslander-Reiten translation on a tube with tubular shift functors associated with tubes. Some new results and examples will be presented.