The present invention relates to the combinatorial use of an siRNA targeted against an endogenous gene to knock out or knock down expression of the endogenous gene in a host and a delivery of a polynucleotide encoding the gene in a delivery vehicle/expression vector to the host to provide expression in the host of the protein encoded by the polynucleotide. The present invention also relates to a truncated form of eIF-5A1 that is useful for inducing apoptosis and killing of cells, especially cancer cells in a mammal.