Complex Structures on Banach spaces with a subsymmetric basis

We prove that a real Banach space E   with a subsymmetric basis and isomorphic to the sequence space E[E]E[E] has a unique complex structure. We also show that if a real Banach space X has the property P, then all its complex structures also satisfies P, when P is any of the following properties: bounded approximation property, G.L-l.u.st, being injective and being complemented in a dual space.