KEAP1 and Hyperkeratosis: Meanwhile, Keap1 mRNA expression in Keap1floxA/floxA mice completely disappeared in the presence of K5-Cre recombinase (Figure 5b), so keratinocyte-specific Keap1 knockout (Keap1floxA/floxA::K5Cre) mice died before weaning due to severe hyperkeratosis of the esophagus, similar to Keap1–/– mice [93].