Anti-XIAP Associated Factor 1 (XAF1, X-Chromosome linked Inhibitor of Apoptosis Associated Factor 1)

XAF-1 binds to XIAP, an inhibitor of caspases -3, -7, and -9, and triggers its relocation from the cytosol to the nucleus (1,2). Overexpression of XAF-1 results in the neutralization of XIAP's ability to inhibit cell death (1). XAF-1 is normally expressed in all adult and fetal tissues but was found to be present in very low levels in a variety of cencer cell lines (3). In contrast, XIAP levels have been shown to be high in a majority of cell lines. Low XAF-1 and high basal expression of XIAP may therefore play a critical role in maintaining survival of cancer cell lines (2,3). Both IFN-a2 and IFN-b can induce XAF-1 mRNA in all cells examined but induction of XAF-1 protein (as observed by immunoblot analysis) was seen only in cell lines sensitive to the apoptotic effects of IFNs (4). Applications: Can be used for the detection of XAF-1 by Western blot at 0.5-2ug/ml. Human spleen cell lysate can be used as positive control and a 32kD band can be detected. Storage and Stability: May be stored at 4°C for short-term only. For long-term storage and to avoid repeated freezing and thawing, aliquot and add glycerol (40-50%). Store at -20°C or colder. Aliquots are stable for at least 12 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.