Figure 1. Independent inhibition of STAT3 and EGFR signaling triggers reciprocal feedback activation in osteosarcoma cells. (A) MG63 and U2OS cells were treated with DMSO (vehicle), LY5, or erlotinib, and the MTT assay was performed to determine cell viability at different time points. Cell migration assay results in MG63 (B) and U2OS (C) cells treated with DMSO, LY5, or erlotinib for 24 h. Magnification, 200x. Error bars indicate SD. ** p < 0.01 vs. DMSO, n = 3. (D). Western blot analysis of phospho-Tyr705 STAT3 and phospho-Tyr1068 EGFR in MG63 and U2OS cells treated with DMSO, LY5, or erlotinib for 24h.