Although the use of the C2 manual shutter decreased the photon count by only 10.6 ± 2.2 grey levels when quantifying light leakage of the microscopy system (Figure 1b,c), this significantly impacted bioluminescence imaging of NF-κB activation in skin window chamber B16F10 tumor-bearing animals (Figure S1g). This evidence concerns the gene NFKB1 and neoplasm.