  We show how our recent results on compositions of d.c. functions (and
mappings) imply positive results on extensions of d.c. functions (and
mappings). Examples answering two natural relevant questions are presented. Two
further theorems, concerning extendability of continuous convex functions from
a closed subspace of a normed linear space, complement recent results of
J.Borwein, V.Montesinos and J.Vanderwerff.
