A, for colony formation assay, SCC47 and Tu212 cells at 200/well were treated with 20μg/mL MM-121, 2μg/mL cetuximab or the combination for 9 days. The medium was changed every three days before cells were stained with 0.2% crystal violet. Cell numbers ≥50 were considered as a colony. ImageJ software was used for colony counting. B, cells (2.5 × 105/well) were cultured for overnight and treated with MM-121 125μg/ml, cetuximab 62μg/ml or the combination for 72 hours and then trypsinized and counted. Error bars are mean ± SE from 3 independent experiments. (* indicates p<0.05 vs. ctrl, ** indicates p<0.05 vs. all other groups).