TP53 and neoplasm: Interestingly, though six other members of the nuclear export protein family have been identified (XPO2-7), XPO1/CRM1 is the sole nuclear exporter for some of the major tumor suppressors (i.e., p53), cell cycle regulators (i.e., CDKN1a) and growth promoting proteins (i.e., survivin) [9–11].