A Universal Lipschitz Extension Property of Gromov Hyperbolic Spaces
  A metric space has the universal Lipschitz extension property if for each subspace S embedded quasi-isometrically into an arbitrary metric space M there exists a continuous linear extension of Banach-valued Lipschitz functions on S to those on all of M. We show that the finite direct sum of Gromov hyperbolic spaces of bounded geometry is universal in the sense of this definition. 
A. Brudnyi and Yu. Brudnyi