CBR1 and head and neck squamous cell carcinoma: Next, we evaluated ROS levels and their downstream protein, β-catenin, in HNSCC cells after treatment with siRNAs against CBR1.  CBR1 inhibition increased the intracellular ROS level compared with that of YD10B, SNU1041 and YD8 cells transfected with the control siRNA (Fig. 5a).