Survivin, a member of the IAP family is an attractive target for cancer 
treatment due to it's over expression in most cancers and low or no expression 
in most differentiated adult tissues. Survivin expression is a poor prognostic 
marker in a number of cancers. Clinical trials are currently underway evaluating 
anti-sense oligonucleotides against Survivin, immunotherapy using Survivin 
primed dentritic cells and peptide mimics that block interaction of Survivin 
with Hsp90 resulting in loss of Survivin protein stability. Additional 
approaches using ribozymes against Survivin mRNA, or dominant-negative cDNA to 
block Survivin function are in pre-clinical stages. Like many genes, Survivin is 
alternately spliced and a number of new splice variants have recently been 
identified. Expression of some of these splice variants correlates with loss of 
steroid receptors as well as the tumor suppressor p53, in some cancers, 
suggesting that like wild-type Survivin, at least some of these splice variants 
may also have prognostic relevance. This review will focus on the current 
understanding of the function of Survivin splice variants and their expression 
and sub-cellular localization in normal and neoplastic tissues as well as 
critically evaluating the potential toxicity of the Survivin directed therapies 
and their predicted effect on the alternatively spliced Survivin isoforms.