Extension of Lipschitz Functions Defined on Metric Subspaces of   Homogeneous Type
  If a metric subspace $M^{o}$ of an arbitrary metric space $M$ carries a doubling measure $\mu$, then there is a simultaneous linear extension of all Lipschitz functions on $M^{o}$ ranged in a Banach space to those on $M$. Moreover, the norm of this linear operator is controlled by logarithm of the doubling constant of $\mu$. 
A. Brudnyi and Yu. Brudnyi