KEAP1 and squamous cell carcinoma: However, squamous cell carcinomas (SCCs) from a variety of human epithelial tissues, including lung, esophagus, head and neck, and skin, often display constitutive activation of the KEAP1-NRF2 pathway through numerous mechanisms, including NRF2 activating mutations (e.g., NRF2E79Q), amplification of the NRF2 genomic locus and loss of function mutations or deletions in the KEAP1 or CUL3 genes [2,[11], [12], [13], [14], [15], [16], [17], [18], [19]].