(A) OEC-M1 cells were treated with MPT0B098 (0.25 μM) for the indicated times. The phosphorylated STAT3 (pSTAT3) and total level of STAT3 were determined by Western blotting. The level of STAT3 mRNA was determined by RT-PCR. GAPDH was used as loading control. (B) Western blot analysis of STAT3 levels after 48 hrs transfection of OEC-M1 cells with control shRNA (NS) or two shRNA constructs (shSTAT3 #1, #2) against STAT3. GAPDH was used as loading control. These shRNA transfactants were treated MPT0B098 for 24 hrs and caspases-3 activity was assessed. The data are represented as mean ± SE; *, p<0.05; **, p<0.01 versus vehicle control. (C) Western blot analysis of endogenous STAT3 protein level in OSCC cells. GAPDH was used as loading control. (D) OSCC cells were incubated with various concentrations of MPT0B098 for 24 hrs and caspases-3 activity was assessed. Data are presents as mean ± SE relative to vehicle control from three replicate experiments. *, p<0.05; **, p<0.01; ***, p<0.001. (E) OEC-M1 and HSC-3 cells were treated with 0.25 μM of MPT0B098 for indicated times. The phosphorylated proteins (p-JAK1, p-JAK2 and p-TYK2) and total level of proteins (JAK1, JAK2 and TYK2) were determined by Western blotting. GAPDH was used as loading control.