  We study the one-loop effective action of the IKKT or IIB model on a
4-dimensional non-commutative brane background. The trace-U(1) sector is
governed by non-commutativity, and leads - assuming no SUSY breaking - to a
higher-derivative effective action. In contrast, the non-Abelian sector at low
energies reduces to SU(n) N=4 Super-Yang-Mills on the brane, with a global
SO(9,1) symmetry broken spontaneously by the background. In the Coulomb branch,
we recover the leading contribution to the Dirac-Born-Infeld (DBI) action,
exhibiting a S^5 \times AdS^5 bulk geometry around a stack of branes. SUSY may
be broken by compact extra dimensions M^4 x K, leading to an induced
gravitational action on M^4 due to the trace-U(1) sector. The one-loop
effective action is UV finite on such backgrounds, and the UV/IR mixing is
non-pathological.
