The expression of XPO1 is increased in a variety of cancer types and the consequent enhanced nuclear export leads to cytoplasmic re-partitioning of numerous cargoes, including many tumor suppressing proteins such as p21, p27, p53, p73, breast cancer gene (BRCA 1/2), retinoblastoma protein (pRB), protein phosphatase 2A (PP2A) and forkhead box proteins (FOXO) (Reviewed in9). Here, RB1 is linked to cancer.