Mdm2 has also been shown to induce expression of the multidrug resistance 1 (mdr1) gene and its main product P-glycoprotein (P-gp) (Kondo et al, 1996), which has been implicated in chemoresistance in human sarcomas (Chan et al, 1990; Hoffman et al, 1999; Jiminez et al, 1999). This evidence concerns the gene ABCB1 and sarcoma.