To directly compare the effects of loss of KEAP1 function to the effects of pharmacological KEAP1 inhibition, we treated wild-type (WT) and Keap1-/- murine embryonic fibroblasts with RTA 405 and assessed proliferation and survival, as well as the levels of IKKβ and BCL2—two other KEAP1 substrates that have cancer promoting activities. Here, KEAP1 is linked to cancer.