Conserved genes that encode inhibitors of apoptosis proteins (IAPs) are frequently overexpressed in human cancers and are associated with resistance to therapy. IAPs contain a 70 amino acid cysteine and histidine rich baculovirus IAP repeat (BIR) and often a zinc binding RING finger. Chen et al. (1999) found that some brain cancer cell lines with high expression of BIRC6 exhibited resistance to apoptosis in the presence of anticancer drugs. Treatment of a high expressing cell line with BIRC6 antisense oligonucleotides reduced BIRC6 expression and reversed the resistance to anticancer drugs.