In summary, the present study reveals that the TK inhibitor nilotinib not only exhibits considerable antiproliferative effects on STS cells, but also, and in contrast to imatinib, sensitizes them to DXR by blocking the activity of the MDR-related proteins MRP-1 and P-gp as well as the DXR-induced expression of P-gp in synovial sarcoma, the latter most probably through inhibition of p38 MAPK. This evidence concerns the gene PGP and synovial sarcoma.