  We analyze open and mixed sector tree-level amplitudes of N=2 strings in a
space-time with (2,2) signature, in the presence of constant B field. The
expected topological nature of string amplitudes in the open sector is shown to
impose nontrivial constraints on the corresponding noncommutative field theory.
In the mixed sector, we first compute a 3-point function and show that the
corresponding field theory is written in terms of a generalized *-product. We
also analyze a 4-point function (A_{oooc}) of the mixed sector in Theta --->
infinity limit.
