APOE and hyperlipidemia: The question of whether the observed differences in the relative SKH-hr2 and SKH-hr2+ApoE mice—such as the number of papillomas, the timing of squamous cell carcinoma (SCC) and papilloma appearance, and the CT-L and C-L proteasome activities—could be attributed to the deficiency of apolipoprotein E and/or the consequent hyperlipidemia exhibited by the SKH-hr2+ApoE mice is a rational one.