The outer automorphism group Out(F_2g) of a free group on 2g generators
naturally contains the mapping class group of a punctured surface as a
subgroup. We define a subsurface projection of the sphere complex of the
connected sum of n copies of S^1 x S^2 into the arc complex of the surface and
use this to show that this subgroup is a Lipschitz retract of Out(F_2g). We
also use subsurface projections to give a simple proof of a result of Handel
and Mosher [HM10] stating that stabilizers of conjugacy classes of free
splittings and corank 1 free factors in a free group Fn are Lipschitz retracts
of Out(F_n).Comment: 32 pages, 9 figure