RAC1 and head and neck squamous cell carcinoma: To confirm blocking RAC1/RAC3 activity increases cetuximab sensitivity with EHOP-016 is not an off-target (RAC1/RAC3 non-specific) pharmacological effect, we utilized short hairpin RNA (shRNA)-expressing lentivirus to knockdown RAC1 or RAC3 expression in HNSCC cells and detected whether cells’ sensitivity to cetuximab increased.