17-allylamino-17-demethoxygeldanamycin (17-AAG), a semi-synthetic derivative of geldanamycin, is a potent antitumor agent that acts by binding to the 90-kDa heat-shock protein (Hsp90) essential to maintain the conformation, stability, activity and cellular localisation of several key oncogenic proteins such as ERBB2, C-RAF, CDK4, AKT/PKB, steroid hormone receptors, mutant p53, HIF-1α, survivin and telomerase hTERT. 17-AAG increases the sensitivity of pediatric acute lymphoblastic leukemia cell lines with varying Bcr-Abl status to imatinib in vitro.