Inhibition of TrkA-induced cell death by its specific inhibitor GW441756. U2OS-TrkA-67 cells were uninduced or induced with tetracycline for 12 h and untreated or treated with the indicated amount of GW441756 for 24 h followed by cell cycle analysis. M1 gate (Sub-G1) includes cell death whereas M2, M3, and M4 indicate cells in G0-G1, S, and G2-M, respectively.