The effect of FLT3LG on activity of STAT signaling pathway and the expression of survivin. (A) MV4-11 cells were cultured with FLT3 ligand at concentrations of 0, 50, 100, and 200 ng/mL for 48 hours; then they were washed, lysed, and subjected to either IP of p-FLT3 receptor as described in Figure 1 or 10% to 12% SDS-PAGE. Western blot analyses were detected with the indicated antibodies for the assessment of expression level changes in STAT pathway molecules and survivin. β-Actin was used as a loading control. (B) MV4-11 cells were cultured in conditioned medium for 0, 2, 4, and 6 hours. Cells were then washed, lysed, and followed by IP and immunoblot analysis. (C) MV4-11-R cells were treated with FLT3LG neutralizing antibody at concentrations of 0, 1, 5 μg/mL, and istotype control antibody for 48 hours. Viable cells and apoptotic cells were counted by the trypan blue dye exclusion method. The experiments were triplicated. Bars represent SD. § and ¶ refer to P values of comparison of the viable and apoptotic cell numbers in 1 μg FLT3LG antibody-treated MV4-11-R samples with those in isotype control. §§ and ¶¶ refer to P values of comparison of the viable and apoptotic cell numbers in 5 μg FLT3LG antibody-treated MV4-11-R samples with those in isotype control. (D) After counting, cells were then washed, lysed, and followed by IP and immunoblot analysis. Densitometric analysis was performed for p-STAT5 using Amersham Image Scanner with LabScan ImageQuant TL software.