MLC1 and head and neck squamous cell carcinoma: Given that the Rac1-p-MLC signal had been reported to play an important role in cell motility by promoting the contractile motion of the myosin light chain, we used interruption approaches with a specific inhibitor to block Rac1 (100 μM, NSC 23766, MedChemExpress, Monmouth Junction, NJ), we found that the cell migration was suppressed in HNSCC cells treated with CCL2 (Fig. 3A, B).