When reporting the sale, you use the ACTUAL Basis, regardless of what the depreciation schedule says.
For determining the Adjusted Basis you do need to use the depreciation that SHOULD have been taken (including the depreciation on any improvements).
Form 3115 does not apply. Using an incorrect Basis for depreciation is a "mathematical or posting error", not a "method of accounting", so Form 3115 does not apply.
As was pointed out above, if the husband died before the property was sold, the Basis gets a 1/2 step-up if they were in a non-community property state, or a full step-up if in a Community Property state. As Dan mentioned, the step-up gets rid of the prior depreciation for the portion that is stepped up.